I found this at Boing Boing:

Simply pull the pin, yell an emphatic “fire in the hole” and lob the grenade into the sleeper’s room. After ten seconds a very annoying and piercingly loud noise (there are three volume settings) will blast out from the alarm. That’s not all however, what makes this especially great is that to stop the alarm the sleeper has to find you so you can put the pin back in. It’s stupid, and brilliant, and will be the bane of every over-sleeper on the planet. Parents are going to love this, though the soon to be rudely awoken might not.

Just check out the customer reviews:

This is one excellent little gadget! Launching in my son’s room every morning and watching him wailing as he tries to find the pin to shut the thing off! Highly Recommended.
Giles
– Southampton

Might work on spouses, too.