Knock knock. Who's there? Flake.

Flake who? Flake out, I'm tired of waiting!

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? Sherwood.

Sherwood who? Sherwood you let me in, it's chilly out here!

Knock knock. Who's there? Sew

Sew who? Sew long, I've been trying to stitch together a decent joke.