The men are lined up for 30 yards, two across, starting at the entrance of a bar on a North Halsted corner and heading down the sidewalk. Inside, the line continues, snaking along the wall from the front door all the way to the back, where it widens into a pool of men, all in various stages of undress. They double over to pull off their pants, or lean against the wall to put their shoes back on. The closer you get to the front of the line, the closer the men in it are to wearing nothing but their skivvies. One guy in Bears boxers helps his friend in flannel shorts lace on a leather armband.

The bar’s weekend dress code involves leather, but this is an Underparty, a semiregular event, and patrons aren’t allowed into the two back rooms unless they lose their trousers first. The bottleneck in the corner is at the coat check, where people are handing over their clothes to be stored in plastic grocery bags on hangers. Some people, apparently familiar with the routine, come prepared to bypass the line. They wear jackets over underwear that can pass for shorts in the street. And some are savvier than others about the logistical dilemmas posed by passing an evening in undies. A shortish middle-aged man asks a taller guy with gray hair and glasses, “What do you do with your cigarettes?”

“Put them in your socks,” is the obvious reply.

Many of the men in the front bar are still dressed, perhaps summoning the nerve to shed their clothes with the help of a few drinks. A tall man with brown hair tries to explain why he’s not in his underwear yet. “I just drank a lot of Diet Coke, and I’m waiting for…”

He doesn’t finish the thought.

“Plus, I’m very insecure about my body,” he continues. “And I’m wearing a bikini. I know it’s tacky. And they’re gray. But at least they’re not white. What do you think about gray?”

He’s got his strategy all figured out. “I put my clothes in a bag, and then I stuff the bag in a corner somewhere,” he says. “I figure that if there’s anybody desperate enough to steal my clothes, they can have them.”

One of the bar’s staff sits in front of a cigarette machine at the doorway leading to the second room. On weekends he’s the leather check. Leather’s pretty easy to identify, but tonight he’s got to make some quick judgment calls. He gives customers a quick head-to-toe exam, sometimes grabbing people who try to slip by in the crush.

A short Asian man who’s still fully dressed points to the sign posted above the leather check’s head–Underparty Dress Code: Underwear, Black Leather, Rubber, Western–explaining the situation to his friend.

One person who doesn’t pass muster is a big-haired woman who comes in wearing an olive blazer over black bra, panties, and pantyhose. Apparently pantyhose don’t qualify; she strips them off on the spot and the leather check lets her through.

By 2 AM the narrow hallway into the second bar is packed with mostly naked bodies pressing against each other; the crowd doesn’t seem to be moving in one direction or the other. The leather check is shouting, “Keep moving, keep the doorway clear.”

This Underparty features a little less skin than previous ones. Because of two recent bar raids G-strings are no longer allowed. (In one raid, at Crobar, several performers were arrested, and in the other, at AA Meat Market, five patrons were charged with public indecency.) The underwear on display tonight is pretty restrained–mostly plain briefs and boxers. Calvin Klein’s stretchy, snug-fitting boxers are very much in evidence, as are his briefs. One man has a trim pair of knit boxers with a long row of small black buttons down the fly.

Lots of people have accessorized. A few are wearing leather harnesses; many more wear leather armbands and beaded necklaces. Crosses and chains and dogtags abound. One man is wearing a floral bikini and a baseball cap. Another guy, a short wide man with a mustache that’s a good half inch longer than his crew cut has combined two costumes: below the waist he’s wearing white briefs and boots, above it he sports a policeman’s shirt and tie.

A chain-link fence sets off an area with a pool table that’s covered with a piece of wood and used for seating. A few people on the table are watching the porn movie showing on the video monitor mounted high on the wall, but more are watching each other. The crush of people continues through this room and into the back room where the dance floor is. There’s a small area left for standing in front of the bar back here, which is along one wall. The other walls are mirrored.

It’s noticeably warmer in here, and more humid, and reminiscent of a 1970s disco. People are dancing and sweating, jostled by other dancers and people circulating. Around the edges of the dance floor couples grope, pressing their flies tightly together. In the far corner, a blonde guy with hairy shoulders wearing white briefs is kissing a guy with glasses in green briefs. In the corner farthest from the entrance, a man shakes a tambourine nonstop.

Next to him a small platform rises about four feet off the floor. Two people are dancing on it: a guy wearing gray briefs and a woman wearing a halter top and a tiny purple-and-blue bikini. She’s got a big purple clip holding back some of her long, straight brown hair.

The woman bends over in front of him with her legs slightly spread and grinds her hips into the front of his briefs. This goes on for a while, but the guy doesn’t seem to be enjoying it much. He finally jumps down from the platform, leaving the woman dancing by herself.