A start.
A bee in a submarine!
A clam shouter.
Student: "So we know when to start Christmas shopping!"
An instigator!
A non-prophet religion Edit: Replace the word "religion" with "set of beliefs" if you're picky about that sort of thing
A full set of teeth.
Someone who knows how to play the bagpipe and doesn't.
It's so inconsiderate! Good thing I was still up playing my bagpipes.