I tell people this fact all the time, and everyone says I am full of shit. But I don't make this shit up, folks. Mormons wear special underwear.
Mormons call these things "temple garments," but normal people know them as underwear. The practice of wearing this special underwear is supposed to remind LDS church members of their consecration to their faith. There is no info on whether or not skid marks would qualify as a desecration of the holy garments.
This is old news to atheists since we find this shit extremely funny.