NEW YORK (AdAge.com) -- When David Letterman asked Twitter co-founder Biz Stone who was his favorite person to follow, Mr. Stone named @badbanana, adding, "I find him to be terribly funny." So does the New York Times, The Huffington Post, NPR and 410,000 people on Twitter, who practically forced him to issue a book of his tweets called "Marching Bands Are Just Homeless Orchestras." Who is this hilarious yet morally reprehensible fruit?

"I'm a 20-year ad veteran, and I've done all 20 years in Nebraska," said Tim Siedell. One year he was at the Clio Awards getting "Hey Whipple Squeeze This" signed by author Luke Sullivan. Mr. Sullivan said to him, "Oh, so you're the guy who works in advertising in Nebraska!"

As @badbanana, Mr. Siedell expresses his hatred of corporate brouhaha -- "My primary objective in any meeting is to end the meeting." Political unrest: "That Indian dinner is so authentic I think I hate Pakistan." Plays on the English language: "There must be a trick to fighting fire with fire because my kitchen just pretty much has twice as much fire now."

So how did @badbanana get his start? "I went into advertising because of the show 'Thirtysomething,'" Mr. Siedell said. Around that same time -- 1987 -- he also saw two movies -- "Nothing in Common" with Tom Hanks, and "Top Gun" with Tom Cruise. "When I saw those movies, it was either navy fighter pilot or creative director, so I went with Tom Hanks and creative director."

Mr. Siedell has a degree in journalism from, you guessed it, the University of Nebraska and, before starting his own agency in 2000, he worked at award-winning Bailey Lauerman. It would appear that a successful business guy would use Twitter to promote his, well, business. Or maybe Mr. Siedell, like Twitter funnyman compatriot @shitmydadsays, could promote his comedy and get a comedy show. But when Mr. Siedell joined the service on March 3, 2007, it was only as a creative outlet.

"I have no huge agenda," Mr. Siedell said. "I recommend Twitter to any frustrated copywriter in order to say what's on your mind. You can use your mind not to just sell dog food! If I have one of those days in advertising where I feel like I got kicked in the stomach, I can turn to Twitter, and the immediate feedback is incredible."

Geeks and non-geeks have come to love the @badbanana twitter stream. Celebrity geek Adam Savage, the co-host of "MythBusters," has said about @badbanana: "In the teeming morass of mediocrity that is the web, someone rises to prominence purely for being smart, insightful, and genuinely hilarious. He makes me laugh every day."