Three women are in a sports club dressing room dressing to play Tennis. Suddenly, a bloke runs through the room wearing nothing but a brown paper bag over his head and passes the three women.
He passes the first woman, who looks down at his unit. "He's not my husband," she says. He passes by the second woman, who also looks down at his member.
"He's not my husband either," she says, also not recognising the unit.
He passes by the third woman, who also looks down as he runs by her.
"Wait a minute," she says. "He's not even a member of this club."
When I first heard this joke, about fifty years ago - yes, really! - the third woman (who wasn't married) said "Well, I'm sure that it's ONE of the club members."