Two Nuns

Once upon a time, there were two nuns...
One of them was known as Sister Mathematical (SM), and the other was known as Sister Logical (SL).
One night they were still far away from the convent, and it was getting dark.

SM: "Have you noticed that a man has been following us for the past thirty-eight and a half minutes? I wonder what he wants?"
SL: "It's logical. He wants to rape us."

SM: "Oh, no! At this rate he will reach us in 15 minutes at the most? What can we do?"

SL: "The only logical thing to do of course is to walk faster".

SM: "It's not working."

SL: "Of course it's not working. The man did the only logical thing. He started to walk faster too."
SM: "So, what shall we do? At this rate he will reach us in one minute."
SL: "The only logical thing we can do is split. You go that way and I'll go this way. He cannot follow us both."

So the man decided to follow Sister Logical. Sister. Mathematical duly arrived at the convent and was very worried about what had happened to Sister Logical. After a short while Sister Logical arrived.

SM: "Sister Logical! Thank God you are here! Tell me what happened?"
SL: "The only logical thing happened. The man couldn't follow us both, so he followed me."
SM: "Yes, yes! But what happened then?"
SL: "The only logical thing happened. I started to run as fast as I could and he started to run as fast as he could."
SM: "And?"
SL: "The only logical thing happened. He reached me."

SM: "Oh, dear! What did you do?"

SL: "The only logical thing to do. I lifted up my dress."
SM: "Oh, Sister! What did the man do?"
SL: "The only logical thing to do. He pulled down his trousers."
SM: "Oh, no! What happened then?"
SL: "Isn't it logical, Sister? A nun with her dress up can run faster than a man with his trousers down."

And those of you who thought it would be dirty, say two Hail Marys!