The term my dad used for "men's briefs", also known as bungees; the kind of underwear accurately described in the tighty whities node as "one of the ugliest items of clothing ever created".

scs gives the American definition of skivvies. In Australia, a skivvy is a long sleeved turtleneck. Thus, in Undone - The Sweater Song, when they say skivvies they are quite likely refering to a sweater. One day, people should forbid common languages to avoid these kind of confusions.