I can’t seem to find the history of it, but it essentially means somethings a bit rubbish, bad, or crap.
Pants are typically underwear in Britain, we wear trousers (Jeans, chinos, suit trousers) over our pants (boxers, y-fronts, briefs) so probably not something you’d want to show off that much.
Thanks for the reference to pants. In US pants covers jeans, chinos, slacks. Shorts are well, shorts. Underwear is our boxers, briefs, tighty-whiteys, etc.
Pants are typically underwear in Britain, we wear trousers (Jeans, chinos, suit trousers) over our pants (boxers, y-fronts, briefs) so probably not something you’d want to show off that much.