clean

To perform a stunt perfectly while involved in an extreme sport such as mountain biking, skiing, snowboarding, etc.

Bro! I just totally cleaned that double! I thought I was gonna biff and splatter my brains all over the pavement!

kack

An injury on the shin typically recieved during mountain bike trials. Caused by the pedals ripping flesh from the rider.

Dude! Check out this gnarly kack I got riding yesterday!