I have a friend who was once picked up by a wrong number conversation.
They called, had the wrong number. Five minutes later, they call back, and said "You had a hot voice, wanna go out?"

The girl turned out to be like five years older then him, so it didn't work out, but they still remained friends.

I'm of the personal oppinion that they got the phone number from a mutual friend and used the wrong number thing as an excuse. But that's far less interesting.