You.
Someone who knows how to play the bagpipe and doesn't.
Because if it were invented anywhere else, it'd be called teethpaste.
Root Beer
Fish muck about in fountains
I always loved this one: (works better said out loud of course) What do you call a fish with no eyes... A FSHHH
A hot rod. NOTE: When I was about 5, I thought this was the funniest joke on earth.