One on a message board who takes care of trolls by reporting them, getting large numbers of users to block them, or humiliating them. There are troll killers who rise to the occasion as needed and there are troll killers who simply do it for fun.
That guy just BRUNED the troll, he's such a troll killer.
The extra leg hair (typically found on males) found beneath the knee that is thicker and sometimes darker than the rest of the leg hair. Knee-beards do not extend into the shin or move up from the top of the knee.