Alec Baldwin drops his pants, jokes about paparazzo on "Letterman"

(CBS News) It was a pants-dropping extravaganza on CBS' "Late Show With David Letterman" on Wednesday.

Alec Baldwin visited the show and within seconds of walking on stage, he dropped his pants.

"I've been trying to diet," he said. "I've lost so much weight ... the problem is that none of my clothes fit me. So, if you put your hands in your pockets, your pants come off."

He then demonstrated it.

Host David Letterman said, "Now I'm thinking, 'Should I take my pants off?'"

After a little bit of audience prodding, Letterman followed suit and exposed his white boxers.

Baldwin's "Letterman" appearance comes a day after he got into a scuffle with a New York Daily News photographer in Manhattan. The paparazzo accused Baldwin, 54, of shoving him, but the actor said the photographer was the aggressor.

"The same guy did it to me before," he said. "He's very masterful at getting really close to you with the camera. You think they're going to hit you in the face. ... They want you to react."

Letterman also held up the front page of the Daily News, featuring a photo that showed Baldwin lunging at photographer Marcus Santos.

"Let's get to it, shall we?" Baldwin told Letterman. "You're obviously burning to hold up the cover of the Daily News."

The "30 Rock" star ended up having a little fun, making light of the incident.

"I think you can see I'm forming the letter 'f" with my mouth," Baldwin joked. "And what I'm saying is - I said to him as I walked up to him, 'What F-stop are you on with the camera?' And he said, 'I'm on a something,' and I said, 'That's not the F-stop ... You have to set the camera on the right F-stop.'"

Baldwin appears in Woody Allen's "To Rome with Love," which hits theaters in New York and Los Angeles on Friday.