When Mormons go through the Endowment ceremony in the Mormon temples, they are given a set of "underwear" known as "garments". Mormons are lead to believe that the garments have "magical properties" and can save them from bullets, fire and accidents. Many faith-promoting rumors are spread throughout the church about the saving powers of the garments - even though not a single rumor can be proven.
Many Mormon couples conceive their children while both wearing the garments. Some women insist that the child be born while wearing garments so that the child would be born "under the covenant". Huge arguments between patients and their doctors ensue when Mormons refuse to take their garments off for surgery.
Mormons are not supposed to wear any other kind of underwear except garments. In all reality, garments in the Church are an absolute control mechanism.