Biggest waste of money you've witnessed?

I don't mind gambling if it's a couple of quid in the IT box, but I have a friend who used to spend practically all his disposable income that month on slot machines. He wouldn't be phased by coming away with about a quarter of what he'd spent, saying that the coffers were full and if he kept playing he'd hit the jackpot. Luckily he's learned to moderate since then.

Also agreeing with the bottled water. I'm sure someone ran a scam once by simply making his own label, bottling his own tap water and selling it at a regular price. A sly trick but it goes to show how stupid some people can be.

I was going to second games and movies that are rarely, if ever played again, since the same guy I was talking about before must have well over 200 DVDs and plenty of games, most of which are scratched to hell due to his untidiness. However, he always seems to know where to get things cheap and it's probably less expensive than renting. Also, if they are in good enough condition, there are plenty of places that would let you trade them in for cash, so it's not a total loss.

Jam it back in, in the dark.