Say, Ernie, want some Ice Cream? Sherbert

Bert : Hey Ernie would you like some ice-cream? Ernie : Sherbert

What did Ernie say to Bert when he asked for ice cream? Sure, Bert!

What did Ernie say when Bert asked him if he wanted some ice cream? Sherbert. (I can't take credit for this amazing piece of comedy. Heard it from a friend, no idea if he came up with it or not.)