Underoos were always treated more as pajama than underwear, but occasionally some Super Kid would wear them to school and the jokes would fly!
Sometimes that kid was me.
I had the Spiderman Underoos. Thank Moses they didn't make Hong Kong Fooey Underoos, I still have a permanent divot in my head from diving into a filing cabinet as a child.
Underoos are still for sale, but seems to have lost whatever charm they had.