I'm going to rub having a girlfriend in my best friends face. He doesn't have one!
Why do you want to rub having a girlfriend to your friend?
My friend wants me to fuck my girlfriend and let him see it so I'm going to do it.
While it's good that you have a relationship, it's not good that you want to rub the fact that you are in one to your friend. Friends should be kind to each other and trying to one up your friend by showing off your relationship when he is single is going to make your friend feel bad and is rude. Instead of doing that to your friend, you should try to help your friend get a relationship of his own so that he won't feel inferior being single.
I don't care.
You shouldn't be doing things like that to hurt your friends. It will make your relationship with them much worse and you won't have anyone to hang out with.