Trolls
Believe in sacred rites of combat. In order to settle disputes, gain in station and influence, or add an exclamation point to one's argument, you challenge your opponent/superior/friend/wife to unarmed combat. This is a pretty serious thing, going on for a good 5 minutes or so (In D&D, that's 50 rounds, AKA forever) due to the Regeneration factor. Because of the same, these fights are never lethal. Trolls believe in Surrendering one's point, argument, or cause when one is rendered unconsious, if it is done bare-handed.

This has caused all manner of dispute with other races, as they believe Trolls to be Warlike and Stupid, constantly killing anyone they disagree with. The Trolls just aren't used to dealing with opponents so breakable.

That said, if one manages to subdue a troll bare-handed, that troll is obligated to defer to you in manners involving whatever argument caused the ruckus in the future.