Lots of comedians have used 'The Tonight Show' as a launching-pad to stardom -- including David Letterman and, obviously, Jay Leno. And on the latest episode (weeknights, 11:35PM ET on NBC), we met a potential new comedy star, by the name of ... Mr. Larry King?

Yes, it's true. Now that he's retired from 'Larry King Live,' the longtime CNN host has expressed an interest in starting a career as a stand-up comic. We swear we are not making this up. So the 77-year-old decided to test his comedy chops on the biggest stage of all. And how did his 'Tonight Show' stand-up debut go?

... Well, Larry told an old-timey joke involving a couple on a train. We won't ruin it, but the punchline is: "Get your own damn blanket!" But the biggest laughs came during his conversation with Jay. Larry reduced the host to fits of odd squeaking giggles -- the likes of which we have never heard from Mr. Leno before.

The giggling began when Leno asked Larry about the age difference between his kids. Jay barely got the question out before he started tittering like a schoolgirl. The answer: King's oldest son Andy is 55, and his youngest is ... 10. The host squealed in delight: "Gah-hahaha!"

"Why is that funny?" Larry asked. Oh, it just is for some reason. But it's also impressive: That a 77-year-old could have a 10-year-old kid, after being married eight times. Mr. King even managed to drive this point home, saying he did it "without Viagra."