It's actually like wearing long-underwear all the time. It's their holy garment. The garment is worn at all times (with the exceptions Kagom mentioned) by members to constantly remind them of their promises they made to God.
I'm in no way defending mormons at all, I hate mormons with a passion, but I hate ignorance as well. Mormons are fucked up, but they aren't all fucked up to the point of doing shit like poligamy and digging people up to baptize them(which is just fucking wrong.)
Yay, way to make assumptions. I do know that only parts of the Mormon belief still practice that. Mormon is just as broad of a term as Catholic or Lutheran. I guess I'll have to be a bit more precise and serious when replying to you.