Knock knock. Who's there? Sew

Sew who? Sew glad you asked, it's a tailor-made joke!

Knock knock. Who's there? Water.

Water who? Water you waiting for, open the door!

Knock knock. Who's there? Pane

Pane who? I'm having a window of opportunity to let you in.

Knock knock. Who's there? A philosophical question.

A philosophical question who? If a joke falls flat in the forest, and no one laughs, was it ever funny?