Knock, knock.
Who's there?
Lettuce.
Lettuce who?
Lettuce in and I'll tell ya.
Knock, knock.
Who's there?
Lettuce.
Lettuce who?
Lettuce in and I'll tell ya.
This joke works 'cause "lettuce" sounds like "let us." You know, kinda like how your brain sounds like a bag of rocks. Lettuce hope you get it eventually, bud.