[vierasmarius]

I think soiling oneself would be highly situational (having more to do with holding it in than any specific trauma), but could potentially be triggered by any Stun result, especially if prolonged stun or unconsciousness occurs. This means it could be caused by Fright, physical damage, a Taser hit, etc. Having it occur would just be up to the GM, and should only be used in situations where it enhances the story (whether dramatic or comedic). Which is to say, I wouldn't have it happen randomly, or often.