Here in New York, Today is the day that the Coney Island Polar Bear Club (or, as my late father referred to them "those idiots") have their annual winter dunk at the beach. They actually do this crazy thing once a week, but they get all their publicity (and presumably, do most of their recruiting) today.
I really don't know what sort of bet I'd have to lose to do this sort of thing. I categorize swimming in frigid water on a 15 degree day along with skydiving, streaking, or running a marathon. I just don't have the guts. I'd rather speak in front of 50,000 people.
Still, God bless them. They pay their taxes and charity does benefit from their efforts.
By the way, if you, like I always thought it was just old crazy guys with too much back hair that do this, you'd be interested to know that many of them are women, and women who look just fine in a bathing suit too.