Knock knock. Who's there? Fig

Fig who? Fig-ure it out yourself!

Knock knock. Who's there? Wendell.

Wendell who? Wendell you give in to the sheer pun-ishment of this joke and finally admit it's been weighing on you, a real heavy hitter in the groan department, making you wonder when 'til the end of this tale of wordplay woe?

Knock knock. Who's there? Accordion.

Accordion who? Accordion to the weather report, it's going to rain!

Knock knock. Who's there? No one.

No one who? Exactly. There's literally nobody here. I just wanted to see if the door was locked.