I don't see a difference. In all cases, I'm probably not "normal" and am thought of as someone who doesn't care about my son or the way he's viewed by others. I feel the sting of worry--what will others think about my son? about me/us? Will he be ostracized and made to suffer for MY choices. It's a little hard not to feel that way. Deal. That doesn't mean you're a prude, just that you're human and live in the world and are affected by it. No one was sprung from the head of Zeus. It isn't easy shaking off years of cultural conditioning.
Not to rub it in, but rather, just to rub in a circular motion with varying degrees of pressure, it might be useful think about these things before they happen. Expect that they will happen and, in turn, hash out your own thoughts about it before you have to do it on the fly. Why set your son loose on the Internet without talking to him about what he'll find there? What he's been watching on MTV, etc. is probably a lot more than some deep-throat kissy face--especially in terms of what those images have probably made him feel, think, and imagine. A 35 year old friend of mine can remember getting thrills out of looking at ads for over the shoulder boulder holders.
Now, you can raise him quite openly and frankly and encourage them to talk to you about it all. Just like you probably do with any other issue--like drugs, booze, driving a car, crossing the road, riding a bike in traffic. You know, preferably they'll discuss their feelings about it with you beforehand. At least afterward. But then again, they might not. There's nothing wrong with allowing them a little privacy either. Despite my mother's very open policy on all these topics, I didn't share with here when I got drunk or when I got laid. That doesn't make me a bad kid or my mom and dad bad parents. And what is hilarious, and I've experienced this myself, my other sister did share *everything* with mom. My mother realized that it wasn't exactly the easiest thing in the world to do: Having manifold discussions with your 20 y.o. daughter about whether she should lose her virginity was a little rough on ma.
So, you'll experience a rush of mixed emotions and thoughts: you will feel pride that s/he's talking to you, you will feel old, you will feel shock. You will want to plug your ears and sing loudly. You will worry about what his friends think and if they'll say anything to their parents and if you'll get a ration of shit for it. You will wonder if you're condoning it and if you are is it a bad thing to do so. Who cares? why do I? ETC.
Talking to your kids about all of this stuff--from riding a bike in the road to having sex to how other people think about these things is important--but doing so won't necessarily make it easy to shake off the ambivalence, fear, or desire to ignore it all. Nor will it guarantee that your kid won't make dumb mistakes.
Kelley