The answer is simple. Drive to your local trail with your clubs. Hike out onto a local trail with a club. When you hear the squeaking of brakes and/or clicking of the freehub, get ready. Timing is key. Swing the chosen club at the unsuspecting MTB. Knock him/her off of his/her bike. Take the bike.
Disclaimer: This suggestion is strictly for entertainment purposes and not meant for actions to be modeled against.