It must be okay for adults to read about oral sex, but OMG think of the childrunz! So the day they all turn 18, they get a primer on all the naughty bits they weren't allowed to know of before because it would warp their precious minds. 17yrs 364 days - sex=evil. 18yrs - sex=okie dokie!
That must be what happened to mine, anyway. Poor, poor filthy mind.