There are probably just as many people who want to see Kevin Federline get smacked as those who enjoyed Paris Hilton's impalement in "House of Wax," and "CSI" is all too happy to deliver. Mr. Britney Spears makes his acting debut with a guest appearance on the crime drama's latest episode Thursday night (October 12) as a street punk who gets what's coming to him.

"He's like a cocky gangster kid, a street kid," Federline said. "He shows up to a crime scene and just kind of talks trash to the CSI guys."

The crime scene K-Fed crashes is under investigation because the most recent incident in a string of attacks has just taken place there. A masked gang of local teenage hoodlums has been holding "Fannysmackin' parties," where they bait and lure Las Vegas tourists to dark alleyways in order to beat them up. Federline's character finds the whole thing very funny, and decides to, in turn, bait the cops digging through evidence. "Did somebody else get a beat-down?" he taunts them. "You bitches haven't caught those cats yet?"

(Click here to view a clip of K-Fed on "CSI")

Hair and fiber analyst Nick Stokes (played by George Eads), who had been squatting near the evidence, doesn't appreciate the jibe, so he stands up and asks, "Excuse me?" as Federline's character starts to insult him, saying, "You're weak, weak, weak, weak." As Stokes walks closer to him, Federline throws up his hands and says, "I'm sorry, you're not weak. You're a joke."

"He's stepping back because I'm steppping to," Eads said. "I say, 'Hey man, step up — step right to me. You can get closer. Come on, get right here.' We're right there, toe to toe, and that's when I give him a good solar plexus."

Though Federline takes a solid punch, he says his character deserved it. "I'd probably pop myself too, if I was talking like that," he said. But when his character tries to take a picture of what happened — he turns to ask the crowd, "Anybody get that on video?" — the cops confiscate the camera.

Federline ends up having a larger — and later to be revealed — role in the episode, which airs at 9 p.m. on CBS, but he was concerned about the audience reaction when news first broke that he was having any role at all on the show. "I've heard tabloids have called up, 'How can you use him?' and da-duh-da," he said. "But everyone around here is wonderful. They've been so nice, and they just stuck up for me. They believe in me."

"From the moment I met him, he's a cool guy," Eads said in Federline's defense. "He's a really nice guy. He just wants to do well. He wants to do a good acting job."

"I was nervous before I did it," Federline said of acting for the first time — he previously appeared on the reality-TV show "Britney & Kevin: Chaotic" and danced on the big screen in "You Got Served." "My wife showed up on set before I did, so I guess that goes to show how excited she was about it. But anytime you need me, I'm ready. I am ready."