(for the record, I can't do any of these):
Juggle
Ride a unicycle
Dunk a basketball
Handstand
Standing back-flip (on the ground/not a diving board)
Throw a knife or ax and stick it
Bounce a golf ball off the face of a club for more than 3-4 times
Keep a wooden paddle ball thingy going
I've always been horrible at stuff like this; can barely make a Slinky go down two steps.