Possible Clues:

• Comedian who said, 'I started a weightlifting program. But the first day, I threw my back out. So I put down the booklet.'
• Falsetto-voiced comedian
• "The other day my nephew's computer beat me at chess. But it was no match for me at kickboxing" comedian
• 'How many people here have telekinetic powers? Raise my hand' quipper
• Speaker of the quip starting at 20-Across