The hypocrite's the one that exists.
Nobody asks, 'who's there ' when you try and tell a knock knock joke.
Don't worry, they'll tell you.
Nothing because ghosts don't exist. Edit:Holy crap I just realized I didn't post this on /r/antijokes.
Nobody has ever seen them directly, but everyone says they exist.
An atheist writer praying his book will sell.
A hypocrite.