Is it normal to constantly do this to someone you find attractive?

He's extremely cute, timid and slightly older than me. I always found his huge butt very attractive, and i love how huge and near-perfect it is, and i find myself staring at it a ton of times.

I talk to him occasionally. And i love hearing his voice cause it fits him, seeing how sensitive he can be most of the time.
Sometimes, whenever i walk past him, especially in a crowd, I'd sometimes reach over and give his big rear a hard slap. One time i did it and emmited a loud "HEY!" from him while his back was turned.

I always find myself sliding my hand onto it and either rubbing or playing with it while we talk. He tries playing it off by laughing a bit sometimes. I would too and would lie and say that I'm only playing around.

Or whenever he's distracted and doing something, I'd slap him on his butt from behind which would cause him to stop what he's doing and freeze. Sometimes emitting a small faint "Hi".

Whenever we aren't hanging out, and are just minding our own business, I'd sneak up on him and slap him back there, startling him at times. Or having him look back for a long time, and then go completely silent.

He's really fun to be around most of the time. And we enjoy the times we have together. He fills me with a lot of joy, and i find him very cute and funny. I find him even more adorable when he's pissed which he is most of the time for some reason.

Almost all people in my friend group and others. tell me that this is okay to do, and something like he'll get a hint and catch on soon, while few scream at me for this.

My friends even tell me something like to move onto sniffing him back there?

Is it normal? I'm in a 80/20 situation right now.