Knock knock. Who's there? Sew

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

Knock knock. Who's there? It's me.

It's me who? It's me, and I'm not here for a joke. I actually need to borrow a cup of sugar.

Knock knock. Who's there? Silence.

Knock knock. Who's there? Existential Crisis.

Existential Crisis who? I'm not really sure, because the concept of identity and self is fleeting and meaningless in an infinite universe.