You wouldn't believe how many students try to 'outsmart' the teacher this way. My wife is a teacher and there's always at least one joker attempting to pull a fast one like the one above per essay.
It gets annoying fast. These people aren't funny, they're retarded. Sure, there are gems in the dirt, but they're as rare as a virgin porn star. There's always somebody to submit something hillarious and original, but as I said -- it's rare.