A priest and a nun are on their way back home from a trip when their car breaks down. They are unable to get it fixed, so they decide to spend the night in a hotel. The only hotel in the town has only one room available. 

Priest: Sister, I don't think the Lord would have a problem, under the circumstances, if we spent the night together in this one room. I'll sleep on the lounge and you have the bed.  

Nun: I think that would be okay.  

They prepare for bed and each one takes their agreed place in the room. Ten minutes later...  

Nun: Father, I'm terribly cold.  

Priest: Okay, I'll get you a blanket. (He does)  

Ten minutes later... 

Nun: Father, I'm still terribly cold.  

Priest: Okay Sister, I'll get you another blanket. (He does)  

Ten minutes later...  

Nun: Father, I'm still terribly cold. I don't think the Lord would mind if we acted as man and wife just for this one night. 

Priest: You're probably right...get up and get your own blanket.