A man and a woman, strangers to each other, find themselves sharing a sleeping carriage on a train. After some initial awkwardness, they retire for the night—the man on the top bunk, the woman on the lower.
In the middle of the night, the man leans over and wakes the woman. "I'm sorry to bother you," he says, "but I'm awfully cold. Could you possibly get me another blanket?"
The woman leans out, a glint in her eye, and replies, "I have a better idea. Just for tonight, let's pretend we're married."
The man agrees happily, "OK! Sure!"
"Good," says the woman. "Get your own damn blanket!"