If anyone had been allowed to give this kind of talk in the schools of my day they would have been met with blushes, sniggers and probably interjections of the "sir, that man just said 'foreskin' variety." I can remember spending a lot of my teenage years nervously patrolling the frontier between the formal language of the adult world and the Rabelaisian badinage of the sixth form common room, worried that I might unknowingly give myself away.
It's not like that today. These 16 and 17 year-olds sat there and lapped it all up with barely a blush. This chimes with my experience of the Kids Of Today. They're a lot more difficult to embarrass than my generation were. Or maybe they're just embarrassed by different things.