For me, it was doubtless those Physika brand basketball-style shorts, back when basketball shorts really meant "basket"… They came in all colours (white, blue, red, dark green, black — I still have the dark green and the black ones, but with time, they became ball crushers).
Best thing, they were wverywhere; everyone was wearing them. Gym class at school was an exercise in not having too big a boner, especially near that hot, super-cute vietnamese dude who had the whole colour set (he was my first crush)…