Everybody needs an ice pack at some point. You can put together a homemade version with a few simple ingredients that won't leak when it melts.
Grant Thompson -- The King of Random -- came up with a creative way to replicate the gel found in most commercially made ice packs. Just pour some water, with food colouring for colour if you want it, into the bottom of a (preferably unused) nappy. The absorbent material at the bottom will take in all the water and turn into a gel-like substance.
Scoop out the gel, stick it in a Ziploc bag, and you're all set. When it melts, it will stay in gel form, so a bag leak won't create a giant mess. No nappies? Try a sponge instead.
QC#30 - Leak-Free Cold Packs [YouTube]