I come over to your place and we all go to your bedroom. You (the guy will strip down naked and sit in a chair facing the bed. We will tie you to the chair then when you are restrained I will strip your girlfriend naked standing about 1 meter away in front of you. I will take off my clothes (by this time I will have a raging hardon) and stick my cock about 20cm from your face and your beautiful girlfriend will suck it right there in front of your face.
After I am happy with her sucking teqnique I will lay her on the bed and get down between her legs to taste her delicous pussy. Once she is nice and wet she will bend over with her face facing you and I will enter her from behind you will be able to see the expressions of lust and pleasure on her face but she is not allowed to touch or suck your cock and you arent either.
Just imagine the intense sexual tension you will feel with this.