crotch watching goes back to our primal instincts to reproduce, only the biggest and strongest won the female. our modern society imposes restrictions on our need or willingness to fight to breed but we still have the instinct to compare ourselves and preen. observe wild animals (lions , elephants, bulls etc) two males wil fight like hell to win the female whilst she calmy carries on eating for she neither knows nor cares who wins, all she knows is whatever happens she gonna get fucked.