Pretty sure they're issued to staff and you can't buy them, they do seem to be higher quality than the usual corporate branded sheite. Had them for a few years now and my plums remain well secured.
LBJ's presidential tapes had him talking to some trouser company, and it's hilarious with "And another thing...the crotch, down where your nuts hang, is always a little too tight" while letting a couple belches out. Teach played it in our Vietnam War class in college to demonstrate how he was a crass character.