Rick Perry jokes about debate gaffe on Letterman

One reason for his brain freeze Wednesday on stage with his GOP rivals: "Hey, listen. You try concentrating with Mitt Romney smiling at you. That is one handsome dude," Perry chuckled during his segment with the comedian.

At the debate, Perry could only come up with the names of two of the three agencies he had promised to get rid of if elected president, ending with a grinning, "Oops."

He also acknowledged that he had "stepped in it" during the debate.

The Texas governor is trying to turn the stumble into an opportunity. He is asking supporters to pitch in a few dollars for every agency they would abolish.

10. "Actually there were three reasons I messed up last night. One was the nerves, two was the headache and three was, and three, uh, uh. Oops."

9. "I don't know what you're talking about. I think things went well."

8. "Hey, I was up late last night watching 'Dancing With the Stars.'"

7. "I thought the debate was tonight."

6. "Hey, listen. You try concentrating with Mitt Romney smiling at you. That is one handsome dude."

5. "Uh, el nino?"

4. "I had a five-hour energy drink six hours before the debate."

3. "I really hoped to get on my favorite talk show, but instead I ended up here."

2. "Hey, I wanted to help take the heat off my buddy Herman Cain."

1. "I just learned Justin Bieber is my father."