Knock knock. Who's there? Sew

Sew who? Sew long, I've been trying to weave a good joke.

Knock knock. Who's there? Sewers.

Sewers who? Sewers *nice* of you to ask, but these puns are really *sewers*-ing my patience, making me think it *sewers*ly time to *sewers*-t out a new joke writer!

Knock knock. Who's there? A door.

A door who? A door has no 'who,' it's an inanimate object.

Knock knock. Who's there? Dwayne

Dwayne who? Dwayne the bathtub, I'm dwowning!