Every mob requires a leader to decide where it is going and what it will do when it gets there. Who decides who leads?

Armwrestling contests
Target shooting to see whose aim is best...hitting the bull's eye wins
Bow & arrow contests...same as target shooting only with bow & arrow, not pistol. DUH!
Building bombs to see whose bomb blows up the most biggest target the most fastest
 
Flip a coin
Boxing...to the death