So I have a policy in my classes that if the entire class gets a 90% or above on a test or a quiz, I buy them pizza. It may seem like a daring proposition to make, but I have to say, in my entire time teaching, I haven't had this happen yet. I've been close several times, but never had it happen.
Until last week. I gave a verb quiz on the chapter verbs and my French 3s all got above a 90%. It was a hard quiz too because there were a ton of irregular verbs (they're working on the chore unit right now). So I am getting them pizza today. Being the end of the month, it's the chapter test, so I'm going to let them munch on pizza while they take the test. Hopefully that is motivation for them in the future (and for other classes) to do well.
I must say, though, thank God for Little Caesars. I don't have to break the bank to get them all a slice of pizza :)