The Diet Coke and Mentos explosion is not a new phenomenon. The idea is pretty simple, dump some Mentos into a bottle of Diet Coke and you have yourself an instant soda geyser. I've toyed with the Diet Coke/Mentos union myself, with mixed, and somewhat messy, results. Apparently though, I had not fully considered the possibilities.
A friend of mine emailed me the image below (no idea where it originated from*). Hosting a dinner party? Then this little trick could be just what you need to spark things up a little.
* Edit: According to a good reader, Tay, it was originally in Wired magazine.