@aidan,
A man and a woman find themselves, due to a booking mixup, sharing the same railway sleeper cabin.
So to save any awkwardness, the man says "You get into the top bunk, and I'll get undressed outside"
When he comes back in, the woman complains of being cold.
-"Okay, I'll fetch you a blanket", he says.
She says, "Couldn't we just pretend we're husband and wife?"
"Are you kidding?" he says, "I'm a gynaecologist."