Knock knock. Who's there? Taco.

Taco who? Taco 'bout a good time!

Knock knock. Who's there? Dough.

Dough who? Dough-n't worry, I'm just here for the bread!

Knock knock. Who's there? Byte.

Byte who? I'm having a little trouble processing your question.

Knock knock. Who's there? Citation needed.

Citation needed who? This joke requires a source to be funny.