A person who stays up all night wondering whether or not there is a dog.
A sixth sense
A linebacker I came up with this on the toilet... Hope it's not old.
Because they can't make a fist.
Arfson
All she does is stay on the dashboard.
Patty O'furniture.
He finishes her drink EDIT: Apparently this is Conan's joke, so all credit goes to him. I just heard it from a friend of mine and I had no idea.
The night before a test.
Who gives a cluck (I wonder if the moderators will censor this joke merely on the grounds that it is categorically terrible )
A: Stay awake and wonder if there's a dog