Then the public schools should teach them those things -- instead of how to put a condom on a cucumber...
Actually, that's a parent's function to teach them what's illegal and such. I had no problem with graphically showing my 14 year old daughter how simple it is for her picture or *any* picture to end up in public on the internet. A girl she knows at school did this with a cell phone (she's 18) and ended up on the internet. I showed my daughter the picture in all its glory. She understood the chain of events that led to it, and that taught her more than anything I could have said.
I also pointed out to her that any nude/pornographic pictures of anyone under 18 gets people shipped off to prison no matter how innocent taking the picture seemed, and she got that point, too. Sadly, there's a lot of teenagers out there who woouldn't have understood such a message. I'd like to think that my child understood it at least in part because of what her mother and I have taught her.
Also, if a teenager is taught more about sex than "Don't", as a lot of parents like to teach, he or she will have a better understand of the several things you shouldn't do lightly, *and why*. I think some of the worst excesses of teen sexuality these days are because the only sexual education a lot of kids get is from TV and internet, and that's because their parents prefer to bury their heads in the sand, and only teach them that you shouldn't do it, but never teach them enough for them to understand why not.