Knock knock. Who's there? Cows go.

Cows go who? No, cows go 'moo'.

Knock knock. Who's there? Wu

Wu who? Wu don't know, I'm having an identity crisis, but I'm paws-itive I'll fur-get about it.

Knock knock. Who's there? Dictionary.

Dictionary who? I'm not defining the terms of this conversation.

Knock knock. Who's there? Pane

Pane who? I'm glass you're excited to meet me, but I'm a little transparent about my feelings.