Mister Schmidt's definitions

Crackerjack

Someone who is a crackerjack, is someone who is greatly humourous, and is able to "crack" you up, i.e, induce a great amount of laughter from you.

Adam: So then I said, that's not a chevy, it's a fjord!

Gary: You're a real crackerjack, Adam.

by Mister Schmidt May 23, 2010