This is a pretty great idea for a prank, harmless enough not to make someone your enemy, but harmful enough to really mess with their day for 15 minutes.

Two guys in Irvine, California just created the Joker Birthday Card. It's like one of those cards that plays a song, only there's a twist.

Once you press the button to play the song, it never stops. Not even when you close the card. Not ever. There are only two ways to get the card to stop playing the song: Destroy it or wait at least three hours until the battery runs out.

The card is up on Kickstarter right now. It costs $15 for one card, $25 for two, or $105 for 10. They're going to ship in July.