Sleeping Carriage

A man and a woman who have never met before find themselves in the same sleeping carriage of a train. After the initial embarrassment, they both manage to get to sleep; the woman on the top bunk, the man on the lower.
In the middle of the night the woman leans over and says:

- I'm sorry to bother you but I'm awfully cold and I was wondering if you could possibly pass me another blanket.

The man leans out and, with a glint in his eye, says:

- I've got a better idea... let's pretend we're married.

- Why not? - giggles the woman.

- Good - he replies.

- Get your own blanket.