this reminds me of a buddy of mine - he's too cheap ( or at least was )
to get a dry suit, so he'd dive his 10+ year old 7mm wetsuit, that was
very full of holes, in 40 deg water. i'm sure y'all have seen those 'hot
packs' that you boil until they become liquid, then to use one you
"click" a disk in the bag and it starts getting cristalizing and getting
hot?
he thought it would be a good thing to keep him warm on a long deep dive
- dropped one ( a big one ) in the back of his suit at waist level, and
away we went. things went well till we got to depth - it seems they heat
faster under pressure - you should have seen him squirming trying to get
that silly thing out! gave himself 2nd degree burns on his a.s. i guess
it worked - he stayed warm :)

PS: this might be better under the stupid things done while diving thread.