Married life

Here is a joke my acupuncturist shared with me:
A man and a woman who had never met before found themselves assigned to the same sleeping car on a trans-continental train. They were each married to other people and were embarrassed and uneasy at having to share the room with someone else's spouse. But they were both very tired and fell asleep quickly, he in the upper bunk and she in the lower.
About 1 am, the man leaned down and gently woke the woman saying, "Ma'am, I'm sorry to bother you, but would you be willing to reach into the closet to get me a second blanket? I'm very cold."
"I have a better idea," she replied. "Just for tonight, let's pretend that we are married."
"Wow! That's a great idea!" he exclaimed.
"Good," she replied. "Get your own blanket."
After a moment of silence, he farted.