i thought it was 'H-O-R-S-E' ,
me & my friends used to play it with frisbee or ball, and if you drop it then you get a letter. only using slightly more vulgar words than 'horse' as i'm sure you can imagine ^_^
i have a couple of those hot gel ones, they're good, but they're only really warm for about half an hour, and then you have to boilthem for 20 minutes to recharge them. i prefer those single use ones, but that's rather an expensive way of doing it. so i might try this