"slurping at a helmet, whipping, frotting, peeing, pooing, squatting like a dog, "
Two men engage in the act of frottage
Public DomainTwo men engage in the act of frottage

To 'frot' is to rub one penis against another, usually until ejaculation.  Frotting has been advocated as a safer alternative to anal sex. It derives from the French 'frotter' – to rub – and came into circulation with Bill Weintraub's article "Frot: The Next Sexual Revolution".

Read more about frottage here.