…from Ken Levine’s blog, …by Ken Levine:

“New Choice!”
by Ken LevineThere was another great exercise for comedy writers in Andy Goldberg’s improv class last Wednesday. This one was called “New Choice!” Two people would do a scene and periodically someone would say something and Andy would interrupt with “New Choice!” The performer then had to devise an alternate line. If Andy wasn’t satisfied he’d again bark “New Choice!” Sometimes it would take two or three lines before the scene was allowed to proceed.
Example:
Me and Fred are in a Costco.
Fred: What are you here to buy?
Me: Cheerios.
Andy: New choice!
Me: 300 rolls of toilet paper.
Andy: New choice!
Me: A case of Trojans and a dozen oysters.
All you have to do is read the full article and you’ll see that KL is a master of comic construction.