There's a new prank that's spreading around the Internet right now that, frankly, would scare you if it happened to you. So in a way, I'm a true hero for telling you about it.
It turns out that if you scratch a message into a banana peel, a few hours later, your letters will turn brown . . . so the person who buys the banana will think they just got a message from a ghost, or a spirit, or a stalker, or maybe all three.
Use this knowledge responsibly.
(Here are pictures.)