MISSION: Suicide Jumper DESCRIPTION: Depressed businessman threatens to leap to his death...from a four foot ledge. DATE: 12/10/05

As far as Improv Everywhere is concerned, what exactly constitutes a prank is up to the maestro. Charlie Todd moved to Manhattan in the summer of 2001 to become an actor. One night a friend mentioned that he looked like the pop singer Ben Folds. He doesn’t, but who the hell knows what Ben Folds really looks like? Todd decided to spend the evening playing the part. His pal teed him up at the next bar: “Hey, aren’t you Ben Folds?” “Why, yes, I am!” Next thing he knew, a brace of British babes had surrounded him. The following night: same shtick, different bar. Shazam! This time the whole place bought it. Photographs, autographs, free drinks. Got some digits, too. Charlie Todd and crew had “caused a scene.”

“The next day I was like, Man, I got to do more shit like that,” he recalls over dinner at an Indian restaurant. And so he did, documenting each “mission” on what began as a bare-bones Web site he dubbed improveverywhere.com. An avid disciple of ’70s performance artist/comedian Andy Kaufman, Todd likes to say the only thing that really sets him apart from other pranksters past and present is that he’s a compulsive archivist. Today improv­everywhere.com offers more than 70 professional-grade videos, a blog, a DVD, and an FAQ section (in case you become overwhelmed). The write-up of his Eureka moment donning the Ben Folds persona is on there. As is the video of him onstage at the Hammerstein Ballroom in November 2006, opening a show for the man himself.

Todd turned to the Internet because he wanted to share a funny story, but he quickly realized its potential to mobilize dormant pranksters. He currently presides over an e-mail list of 22,000 would-be agents, hungry for action, awaiting orders. Such power comes in handy when you want to storm Abercrombie & Fitch with bare-chested men—111 people showed up for that one—or wreak havoc at Best Buy by flooding the place with blue polo shirts and khaki pants. “Thomas Crown Affair! Thomas Crown Affair!” a bewildered manager blurted into her walkie-talkie. The group has fooled a crowd of New Yorkers into believing that U2 was playing a free surprise gig from a midtown roof and convinced shoppers at a local Barnes & Noble that Russian writer Anton Chekhov was giving a reading. Chekhov, of course, died in 1904.

“I’ve always thought of Improv Everywhere pranks like getting stabbed with an icicle,” said Todd Simmons, an aspiring actor and accomplished agent who played the role of a tuxedo-clad bathroom attendant in the men’s room of a McDonald’s in Times Square. “Once people notice a crime has been committed, all the evidence has evaporated.”

MISSION: Even Better Than the Real Thing DESCRIPTION: Fake U2 performs a rooftop concert. DATE: 5/21/05

It was the simple genius of “Frozen Grand Central” that pushed IE into the international spotlight. More than 200 agents with synchronized watches gathered at the station, and froze, all at the exact same time. They stayed stuck for five minutes. “That’s the craziest shit I’ve ever seen, and I’m a cop,” a police officer on duty remarked. The video was posted in January 2008 and almost immediately went viral. More than 16 million people have clicked play. According to Todd, other groups have reprised the gag in 100 cities.

One of Improv Everywhere’s guiding principles is that theirs are victimless crimes; the goal is to give witnesses a laugh and a story to tell, not to humiliate anyone. Humiliation, however, remains one of the vital components of many a good prank, hoax, or practical joke. Think of Justin Timber­lake crying over his foreclosed home on Punk’d, or Sarah Palin fooled into answering inane questions from the faux-president of France last fall. No one has done a better job of tapping humiliation’s potential than Sacha Baron Cohen, whose willingness to embarrass not only himself, but his victims (and they are victims) has helped make him one of Hollywood’s biggest stars. Like Andy Kaufman before him, Baron Cohen goes all-out when he commits to a role. TheSmokingGun.com recently revealed more than two dozen fake production companies he created in order to fool unsuspecting dupes for this summer’s Bruno. As Ali G on HBO, he pulled the wool over the eyes of everyone from Pat Buchanan and Newt Gingrich to Noam Chomsky and Boutros Boutros-Ghali.