Mark shows you how to perform a chin crusher. This movement is a slight variation of a skull crusher. Instead of bring the bar down to your skull, bring the bar down to your chin and extended up. This video best demonstrates:
http://www.youtube.com/watch?v=aVnepQUVuMc
Suggested sets and reps for a Chin Crusher: 3 sets of anywhere from 6 to 12 reps. Suggested Tempo: 3121