Knock knock. Who's there? Isadore.

Isadore who? Isadore a lock on this door, or is it just glued shut?

Knock knock. Who's there? Dictionary.

Dictionary who? I'm not defining the terms of this conversation.

Knock knock. Who's there? Maple.

Maple who? Maple syrup to talk to you, I've been feeling a little stuck.

Knock knock. Who's there? Parenthesis.