What you have experiences is probably not that unusual, as you can see on the answers you have already got. Last winter I went with my son and 2 of his friends to the montains for skiing. The first afternoon 2 of them, incl. my son, came home with wet the pants and they tried to convince me it was quite usual for snowboarders to let go in their waterproof snowpants rather than going home to the cabin or trying to find a rest room. I was quite angry and bought a pack of diapers which I placed in their room with the clear message that the next one coming home wet would have to wear diapers for the rest of the week, incl. the trip home. They did not wet again during the rest of the stay. After that my son to my knowledge has wet the pants twice, once was obviously on purpose as he didn't want to leave the movie "Lords of the Rings! to go to the rest rooms. He then again got the message that I still had those diapers purchased during the winter wacation, and next "accident" would mean that he was going to wear them. He was quite embarrassed and promised it would not happen again. The fear of having to wear diapers obviously had an effect of my son and his friends. If I were you I would tell your son that if he comes home wet again he will for the future have to wear diapers when out sleighing, hopefully you will have the same positive effect as I and others here have had.