The effect is best at dusk, when dramatic floodlighting tranforms the scene in the second story louver window from “display” to “spectacle.” A huge reproduction of one of Andy Warhol’s Marilyns gazes, with sultry nonchalance, out toward the South Street tourists. She is flanked on both sides by a small army of headless alabaster mannequins, their modesty protected by brightly patterned boxers and snug tighty-whiteys, respectively. Two of the boys sport vintage bubble Christmas lights wrapped festively — in bondage fashion — around their torsos. None wear shirts.

The site of this Pop art tableau is Philadelphia AIDS Thrift ­— PAT for short. Located one block south of South Street (unofficial neighborhood motto: “You’re okay! We’re So-So!”), PAT is a charity thrift store now entering its fifth year of operation. The store’s profits from the sales of clothing, furniture and general bric-a-brac are donated to Philadelphia’s AIDS Fund, which in turn funnels money to thirty education and treatment organizations throughout the city. Additionally, PAT provides these organizations with a number of free vouchers that affected clients can bring to the store and redeem for clothing and housewares. This weekend PAT celebrates not only its fifth birthday but also the achievement of another milestone: as of this month, the store has donated over $200,000 to the AIDS Fund.

“It’s a really nondescript building,” admits co-founder and manager Tom Brennan of the space at 514 Bainbridge St., where crepe, velvet and satin linings of coffins were once manufactured. “I mean, there’s nothing interesting about that building. It’s just a red brick box with old industrial windows on the second floor. But it’s what we could afford and it’s what we got, so we just try to make it work.”

And make it work they do. Like a tiny, trolly Olsen twin disappearing under yards of fabric and kilos of jewels, PAT’s plain brick skeleton is completely concealed by ostentatious kitsch. It’s not that the PAT crew — comprised almost entirely of volunteers, plus a small handful of employees — has put the plainest girl in the prettiest dress. No one would ever mistake the facade for something elegant or beautiful. There’s just something endearingly ramshackle about the bright signs, psychedelic flags and jumbled racks of clothing barnacled to the building’s exterior. They vie for visitors’ attention like flashy, boisterous children, distracting the eye as much from each other as from the other businesses on the block. It’s the decorative equivalent of Lady Gaga rocking a dress made of severed Kermit the Frog heads — not beautiful, per se, but an enjoyable distraction.

Brennan has spent the past half hour hunched on a dirty metal folding chair in the back room of the thrift store’s furniture-selling extension, officially named “PAT’s Pair-o’-Dice Garage!”, located catty-corner to the main storefront on the opposite side of Bainbridge. The corner where Brennan sits is obscured from public view by an asparagus-colored curtain onto which a classic PAT-style sign has been stapled: a beaming Borat, thumbs fixed firmly northward, appears above the words “Staff Only.”

The store’s clothing donations are kept behind this curtain. A veritable hillock of garbage bags is piled up from floor to ceiling; mounds and heaps and tons of them spill forward out of hidden depths. Even Brennan’s 6’3” frame is dwarfed by the tower of gleaming black. It is a terrifying, thrilling sight.

As with other nonprofits, donations are PAT’s lifeblood. They tend to come in waves that range in size from ripple to tsunami. On a busy day, PAT can receive 1,000 pounds of drop-offs, a half-ton of “stuff.” Recently, one voracious collector left the entire contents of a house to the store after he deemed it financially unfeasible to ship his stash from Philadelphia to his new homestead out West. Though the collection has yielded some great treasures (a celadon-colored Louis Vuitton store mannequin, Civil War-era ladies’ bonnets and mounds of collectible Fiestaware), it has also brought forth many disappointing finds (boxes and boxes of wet maps). A few PAT workers have spent the summer emptying out the house. Though the store’s cup of donations runneth over for the moment, it’s not a bad problem to have.

The bulk of PAT’s clothing processing (that is: sorting and pricing) is done in the looming shadow of the aforementioned garbage bag pile, in a charmingly ramshackle wood-and-tarp construction set up against the warehouse’s huge garage doors. Known semi-affectionately by staff as “the Igloo,” this structure is characterized by wild temperature fluctuations. “Freezing in winter, suffocating in summer,” is the basic template employees use when describing it.

Brennan is spending his Saturday evening hunkered down here, judging other people’s cast-offs. Soundtracked by Belle and Sebastian B-sides and his own constant low murmuring stream of chatter, he’s separating the potentially saleable clothing donations (sweatshirts, cocktail dresses, Doc Martens) from the absolutely un-saleable ones (used underwear, ripped t-shirts, unmatched flip-flops).

Items that can be sold in the store are set aside to be priced and will likely end up tagged within the range of one to eight dollars. Those that are deemed sub-par are bagged up and recycled: the store sells them to a rag company for pennies on the pound.

Brennan paws through the pile of used women’s clothing before him with a raccoonish intensity, his head of close-cropped salt and pepper hair bobbing up and down as he works.

“So, the thing about sorting,” he explains as he digs, “is that you learn a lot about people from their bags. It’s thrift store archaeology … anthropology. It’s really great!”

Suddenly, he opens what he can almost instantly identify as “a stripper bag.”

“We get a lot of strippers donating and buying stuff,” he says, rifling through the bag’s contents. “And always in the stripper bag, you got: stripper boots.”

He nods at the scuffed plastic bin of shoes to his left.

“A schoolgirl outfit or a French maid outfit … some rhinestone thongs.”

He pauses mid-dig and peers into the bag expectantly. A satisfied grin spreads itself across his face. He continues.

“And, every stripper bag — ” he pauses as he dramatically reveals his find “ — The Lovely Bones! A copy of The Lovely Bones!”

Brennan brandishes a hardback copy of Alice Sebold’s 2002 novel triumphantly before him.

“Every stripper bag! It never fails!”

Back across the street, a few passersby are taking advantage of the warm September weather to examine PAT’s sprawling sidewalk presence. The store literally spills out into the road, encroaching on walking territory in a way that would be utterly forbidden only a street away, on South. Racks of one-dollar t-shirts and tables of curios crowd the front display window, lending the walkway a sweetly raucous, jumbled appearance not unlike that of an outdoor marketplace. A few paces from the entrance, huge plastic bins marked “FREE” hug the curb. These are always filled to the brim with stuff. There's just no other way to put it. Mothering magazines. Early twentieth century grammar textbooks. Christmas lights shaped like carrots. Just stuff, all of it free.

If possible, the store’s interior is even more chaotic than the outside. The space attracts tchotchkes like a kitsch coral reef. "When people walk in, we want them to think ‘What is this place?’ We want it to be the most eccentric, confusing, amusing place they’ve ever been,” says Brennan.

Throughout the day teenagers take pictures of themselves posing with PAT’s comical signs and wizened-looking mannequins. Mission of eccentricity: accomplished.

A few yards to the left of the ground floor entryway hangs a backlit Bruce Lee poster, inviting people to check out the “Second Floor of Fury.” This is where PAT houses its vintage clothing section, beloved by the twee Etsy set. Those wanting to take Bruce up on his offer are forced to navigate the narrow kitsch-kaleidoscope that is the store’s steep, claustrophobic staircase. Not a speck of paint is visible on the walls here covered, as they are, by movie posters (Mommie Dearest, The Virgin Suicides and Rocky Horror), birthday cards and, most eye-catchingly, a pin-up girl collage created from an old page-a-day calendar. It’s tempting to linger in this area, to take in as much of the decor as possible. Unfortunately, frequent stairwell foot traffic makes loitering difficult. To visit PAT is to experience an extreme case of sensory overload; it’s impossible to see everything at once.

“I think you definitely have to make more than one trip here,” says PAT regular Valerie, pausing in the vintage section. “It’s such a hodgepodge of things. And there’s constantly new stuff coming in, so, if you don’t find anything that’s your style, you have to keep coming back.”

Nearby, a stony white mannequin with a witch’s wig of black hair rises lurchingly up from a circle of bulky men’s suit coats. The mannequin’s nails have been markered-in a bizarre shade of salmon-beige — perhaps a former owner’s misguided attempt to make her appear more lifelike (or at least less horrifying). PAT’s design team has opted, naturally, to play up her worse-for-the-wearness by dressing her in a sumptuous white wedding gown. She looks equal parts haggard and sinister.

“It’s a treasure hunt,” agrees Jill, the owner of another thrift store located a few minutes away. “It’s just a fun place to come. The music is good and it’s fun to shop here.”

It is impossible, it seems, to describe PAT without mentioning the music. For one thing, it’s frequently a little too loud. One could drown out the sound with headphones, yes, but it’s much harder than combatting the passive muzak of department stores. It’s also impossible to escape. The store is a musical minefield with speakers hidden high and low, melody emanating from every corner. Even venturing outside does little to dull the effect, since exterior loudspeakers pump music onto Bainbridge to draw passersby inside.

Those concerned they will not find the music selection to their tastes need not worry. The medley is the definition of eclectic, with about a quarter of a million songs shuffling through the store’s two eight-hundred-disc players at any given moment. If a genre of music has ever existed in history, odds are good that a representative track will, at some point, come flooding through PAT’s myriad, inescapable speakers. In a few weeks the store will be celebrating the musical achievements of one of its own when local band Dangerous Ponies, featuring PAT employee Brooks Banker, have their record release party on site.

“It’s a truism that nonprofits attract neurotic people,” admits Brennan. “We’re all clearly a little bit crazy. I mean, we’re willing to spend our lives surrounded by just mountains and mountains of junk.”

“I feel like [the store] reflects the personalities of the people that work here,” agrees Christina Kallas-Saritsoglou, who, in addition to being Brennan’s co-founder, serves as the store’s volunteer coordinator (and, she claims, unofficial psychiatrist). Indeed, the staff is a huge part of what makes PAT, PAT. Their fingerprints are all over the store, marking everything from the bizarre displays (a mannequin, the bottom half of her face gutted and replaced by a jumble of wires, dressed up like a chef, complete with pockets full of knives) to the special messages handwritten on price tags (“You look lovely, Mrs. Draper!” reads one attached to a vintage evening gown hanging upstairs).

“But I think that another thing that we want to create,” she continues, “outside of just this, awesome, weird kind of vibe, is a safe place for people. We really want it to be a place for people to come and feel at home and connected and I think we’ve succeeded in doing that. I love that we’ve created this thing here, this family. Dysfunctional as it may be, it really feels like a family.”

Those looking to become a part of the PAT family, either as volunteers or work-study employees, should contact Christina Kallas-Saritsoglou at phillyaidsthrift@aol.com.

For more information on this weekend’s PAT celebrations, visit http://www.phillyaidsthrift.com/