Don’t do this. Kids are just that - kids. They experiment. “Oral sex” is not what they think it is, and even if they do, they’re just figuring stuff out. It’s probably now a good time to have “the talk” with your son, but I wouldn’t go jumping to telling people as if it’s a problem. You’d be surprised at how many kids to weird shit just to experiment, and there’s nothing wrong with it. These kids probably don’t have a real sex drive yet, and if they do they have no clue what they are doing. I did all sorts of weird stuff at that age. Don’t shame them, just use it as an opportunity to talk about the birds and the bees with your son, and that if that’s what they’re feeling, it’s okay for it to be the bees and the bees.