when I was in pre-calculus, my teacher let us bring notes into our final exam. the catch was, the notes had to be written on a fruit. and you had to eat the entire fruit before you left (i.e., you could write a watermelon's worth of notes, but you had to eat the whole watermelon.)
looking back, I didn't have a lot of common sense back then. I got one of these spiky guys, because it looked cool and I wanted to try it. But it was VERY hard to write notes on. and it tasted...well, not very good. bitter, but a little banana-y. I wouldn't recommend them.
my teacher finally felt so bad for me that she let me leave without finishing it.