blood compass

Especially useful for adrenaline junkies, and those who love all things to do with the great outdoors. If some crazy maneuver, jackassesque like stunt, hard fall, or animal attack results in blood you now know you should adjust, prepare or tweak your attempt #2 (or #3-100) accordingly. Hence the event that rocked you to the point of bleeding has become your blood compass.

"Damn! Did you see how bad Gavin road-rashed his face after attempting that small-margin-for-error landing from skydiving with skis on?"

"Yeah, he got fahked up! That move is definitely his new blood compass now."