Carefully monitoring the "level" of your pants' waistband so as not to reveal your "plumber's crack' when working in public.
"Watching the bottom line" can also refer to a bystander's lengthy observation of someone who is unknowingly "mooning the world" while engrossed in the task he's performing. Sometimes you can gain a bit of extra folding-money if you make a bet with anyone else who's with you about how long it'll be before the clueless butt-exposer either realizes his faux pas or someone else yells at him to pull his pants up.
by QuacksO June 21, 2019