Asklemmy

Well, it reads as just silly kid stuff. Kids do dumb shit because they're kids.

The important part is whether or not it was traumatic to you, not whether it was sexual, or abuse, or sexual abuse.

It doesn't seem like it did. It seems more like it was just weird and that was that, and that you're looking back on it as something more than it was then. This isn't to minimize your experiences, it's just saying that your phrasing and the question itself point towards it not being traumatic at the time.

Was it inappropriate? Yeah, but it's very likely nothing bad was meant by it. Even if it was sexual on his end, that doesn't mean he was intentionally breaking consent in a conscious way, or that kids making mistakes like that is inherently a bad thing overall. Something can be inappropriate, but not wrong because if someone lacks the capacity to understand that it's wrong, it just isn't the same thing as when they do, and choose to perform a hurtful act.

Me? I think I'd just let it go and not worry about it if possible. If it isn't possible, then it might mean there's issues with it that need resolution with external help, so the attempt to do so kinda serves as a self diagnosis. If you're able to easily put it aside, then it wasn't traumatic (or not enough to matter).

It may help you to know that that kind of thing is super common. Over on reddit, there was a sub called morbid questions, and I couldn't begin to tell you how often people would ask what you're asking, with the same or similar circumstances. Kids get dumb ideas, and lack the inhibition to not act on it. Kids can engage in sexual abuse, yes, but there is a difference between that and just doing something rude like slapping an ass. It's about intent, extent, and situation.

It may also help to know that, even if your friend did intend it as a sexual act, and did so knowing that it wasn't acceptable behavior, that you aren't obligated to feel any specific way about it. You don't have to feel the same as someone else might; you don't have to be okay with it because someone else is, you don't have to be upset because someone else is. Your experience is yours.