A *cow*culater. I made it up myself, so don't groan at the pun.
It was homophonic.
It taint yours and it taint mine :D (Puns for the win :D)
He put it in a conviction-oven.
None, that's what students are for.
Sir. Groan worthy penguin jokes(https://allwrong.wordpress.com/2007/10/05/penguin-riddles/)
A math problem.
They're all, like, equal to me...