Why do guys like grabbing girls butts?

Why do guys like to grab thedir gfs butts and stuff like that??? Some people say they get pleasure out of that but how???

...I will become infamous on this website for making girls mad. Seriously, stop making stereotypes. What if I said 'Why do all girls act like sluts?'? I bet you would say 'I AINT NO SLUT AIGHT' In other words, I can't answer your question because I don't do that, and not every guy does it, as you put it.

Means you sexually enjoy the girl or you want to have intercourse.
Seriosuly.

...because girls' butts are awesome.