My favorite was my Alg2 final last year. I wrote one word on each line, so if you read down the paper it said "What's the point of this class? Have I ever told you I really hate you?"[There was more, but you get the idea] And on the paper we were supposed to show our work on, I drew goldfish, unicorns, etc.
My friend topped me with the Alg2 final though: she colored a rainbow across the entire thing with colored pencils.
We both passed the final.