A man and a woman are seated next to each other on a flight.

They start eyeing each other, and both realize they want to do the same 
thing. He slips a condom out of his pocket, and she looks delighted.

Rear toilet? He suggests.

Five minutes, she agrees and goes off. 

He waits five minutes, then goes and slips in there with her. Right, get 
that condom on she says. Soon, they are both sighing with pleasure.

But a sharp eyed stewardess has noticed them, and realized what they 
are up to. 

So, she humiliates them by making an announcement over the 
PA system. "To the lady and gentleman in the rear toilet, we know what 
you are doing, and it is expressly forbidden by airline regulations.

Now, please put those cigarettes out and take the condom off the smoke 
detector."

And what were you thinking?

I worry about you sometimes!