LOL. Not quite what they look like. The Mormons will claim they are ‘sacred not secret’ but you can get near replicas of the women’s (sans the special markings) at JcPenny’s in SLC.
For non-mormons or non-temple mormons some people will wear the replicas (for women) or undershirts and long boxers (for men) to appear “temple LDS”. It is not ucommon for LDS to do ‘garment checks’ on people to see if they can trust them.
Here is a link to a jpg of the actual ‘holy underwear’.
http://www.getreligion.org/wp-content/photos/Garment.jpg
Not to put too fine a point on it, but TSA and perverts do the same.
All due respect to sacredness and everything....