Rugby scrum with a difference we can all see.

All those naked male bodies grappling and rubbing against each other, no doubt getting sweaty, the obvious question is.....why don't they? Are they so absorbed in the game that their own animal feelings are 'held down' for the entirety of the match? And how do they tell quickly in the heat of the moment who is on which side? (Hoods v. Skinheads?) I'd sure pay good money to be one of the spectators.