Because their heads are so close to their bodies!
Gnome : Put a five pound note between his teeth and stick his head over the side of the sledge.
A: A baby with a javellin through its head.
A Kid replied: The legs... Because everynight I see my mum's legs up high and screaming "OH GOD! I'M COMING!! XD
They both are insulting, but the skeleton doesn't have any body to share racist jokes with!
Look out for the mice!