Monkey has a SERIOUS post-it fetish, too...
In particular the little strip ones that you use for marking pages etc. I use loads of them to mark stuff in books and magazines, and Monkey does his best stealing them. He drives me crazy sometimes!
As punsihment, I occasionally put one on his forehead. It's the funniest thing in the world watching him crossing his eyes trying to see it, and working out how to get it off.
Ok, maybe not very kind... but he started it! I have to get my revenge! (And also... he seems to enjoy it.)
Funnily enough, he is also crazy about emery boards... I have had to hide all of mine - he used to steal them, and I'd find them in the oddest places.