Corey spends a night in jail with IBS.

I once did jail time. My crime? Listening to Scott Klein.

He's the friend who told me to ignore the speeding ticket I got just before relocating to L.A.

"New York and California don't share computer records," Scott said. "California won't know and you won't have your New York license anymore."

He was right about California's obliviousness. I traded in my license and saved $90.

Four years later, I made an errant right on red while visiting my girlfriend in Queens. I gave the officer my squeaky-clean California license. He gave me my Miranda rights. Running my name and birth date revealed the bench warrant.

"Sorry, this used to be just a citation," said the station sergeant. "But now we have to hold you for 24 to 48 hours. Talk to Giuliani if you don't like it."

It was part of what the former mayor called his "quality of life" initiative. Someone guilty of a minor infraction was probably guilty of more serious crap the cops should take their sweet time researching.

I doubted Rudy would talk to me, though, so I used my one phone call on my girlfriend.

"Really," I told Kelly, "this is no joke."

That's just what I would say if it was a joke, so 10 minutes of convincing was required.

At midnight I was transferred to Central Booking, an ammonia-reeking maze of a dozen cages. My handcuffs were removed and my mug shot and fingerprints taken.

A dozen men sat on a metal bench in the first cage. The one next to me wore scrubs. He didn't look like a surgeon. I tried suppressing my curiosity but thumb-twiddling only kills so many minutes. I introduced myself to George, who explained his outfit.

"They got me from the hospital," he said.

Two silent minutes transpired before I summoned the nerve to inquire why he was hospitalized.

"A cop shot me."

This time, 5 minutes. When I asked why George was shot, he shot me a look that burned through my face, charring the cement wall behind me.

"Let's just say the other guy deserved it," he said.

The next cage wasn't nearly as much fun. It was the same size but crammed with 50 men and no bench. In the center was a toilet, encrusted with new and old feces, and it gets worse. The only drinking water came from a fountain mounted precisely atop that toilet.

I noticed a hierarchy. Along the back wall sat the baddest asses, probably murder suspects like George. The middle was standing-room-only, reserved for your friendlier felons. And desperately clutching the bars, hoping the guard didn't look away, stood us sissy misdemeanors.

Other than me, there was one other white guy. He was passed out drunk on the floor, getting kicked by the friendly felons. They laughed when he didn't wake up. I laughed, too, since I didn't want to be next.

Food arrived at 4 a.m. Rice Krispies and whole milk, no bowl or spoon. You down the box of cereal, then the box of milk. My new friends removed the drunk's left shoe, poured cereal and milk in, then put it back on.

Problem: I'm lactose intolerant. Soymilk is not served in the New York City penal system. So what? I was hungry. Besides, the lactose intolerance thing was probably in my head.

4:25 a.m.: It wasn't. I had gas, angry gas, and it demanded instantaneous expression. I fought it. It fought back, shooting up behind my eyeballs. It flapped around there like a caged bat.

It wasn't clear which would be more hazardous -- rupturing my internal organs or decrepitating on my cellmates. But my blood was slowly carbonating. A "silent but deadly" was required.

When my next wave of involuntary flatulence arrived, I opened my rear more gingerly than you would a can of beer rolling to a stop from a moving car.

The discharge was silent. But lactose-intolerance farts are not good farts. Plumes of stink sprouted from my rectal escape hatch. A whisper came from the gangbanging VIP section, which my intestinal distress had reached.

"Who farted in my face?" it asked.

A bad-ass murderer dude got up and repeated his question, louder.

"Who farted in my face?"

We misdemeanors cowered. I exchanged "not me" glances with the one next to me, a ringer for Rerun from "What's Happening."

"Who farted IN MY MOTHERF***ING FACE?"

In the moment the guard picked to turn away, the bad-ass coiled for a kick. Rerun's back was the target. Apparently, he looked more like an indigestion sufferer than me.

The force squashed him into the bars. Under his clothes, he must have resembled a charbroil-lined hamburger.

My first instinct, relief that I got away with it, was quickly replaced by dread. I had between 17 and 41 hours left, and my next fart could be my last in life. I would receive a beating not only from the bad-ass, but also from Rerun, for letting him take my earlier beating.

Farts kept appealing to me for release, but I kept my cork tight. You'll get out when I do, I told them.

Luckily, the next cage-switch came within the hour, and the felons were ferreted out. We misdemeanors made our way from one smaller cage to the next, the moves providing perfect methane-release cover. In the last cage, a door led to the back of a courtroom, where my misdemeanor was lowered to a traffic infraction and my ass was lowered to a proper toilet.

They say jail is a learning experience. Here's what I learned: 1) lactose intolerance is real; 2) never take legal advice from Scott Klein; and 3) it's true what they say: jail is a good place to work your ass muscles out.

If there's ever a sphincter-holding Olympics, I'm qualified.