Ask Not On Whom the Bell Tolls

If you can hang a small bell (a Disneyland bell, in this case) on someone's back belt loop, it will jingle, jingle, jingle.

Best of all, your target won't notice it's there for a while. What a great idea! (The source site is a little salty, so I won't track back to it...and it looks like it's on hiatus anyway.)