A guy is riding on the bus and sees the most beautiful woman he has ever seen get on. The only problem is that she is a nun. He decides to approach her anyway. "Sister, you are the most beautiful woman I've ever seen and I must have sex with you." he says.
"I'm sorry but I've given my body to God" she replies and then leaves.
Suddenly the bus driver turns around to the guy and says "I know a way you can get her in the sack." The bus driver tells the guy about how the nun goes to confessional everyday at 3 in the afternoon. The bus driver tells the guy his plan and the guy leaves happy knowing he's going to get some.
The next day at 3 the guy is in the confessional booth dressed as a priest. When the nun approaches in the darkness he says "Sister, God has told me I must have sex with you."
She replies "Well if God has said it, we must do it. However because of my strong commitment to God I will only take it in my butt."
The guy figures this isn't a problem and proceeds to have the best sex ever. After it is over he whips off his outfit and says "Surprise I'm the guy on the bus!"
With that the nun turns around and says "Surprise I'm the bus driver."