Why do men like to slap a woman on the (clothed) butt? Is it a sign of their confidence or dominance?

Yeah I like it. It's a show of dominance. But it's a turn off if the Guy doesn't take a little roughness back.! Last nite I was excited and scratched his back and he was like easy w the nails. Meanwhile he can amack my butt.? It's like man up dude. He should ger as well. as. As give