Jenny was sitting reading her favorite magazine when suddenly an ad pops for an all-expenses-paid cruise for the low price of $500.
She excitedly goes to Jack, her husband, and shows him the ad. "Look Jack," she says, "it's in two days and only $500!"
"I'll be honest with you," said her husband, "I have too much work for a cruise. How about you go and have a good time?"
His wife is a bit disappointed but bounces back and decides she will have a good time anyway.
The next day, Jack is in his office when his co-worker, who is also his mistress, comes to him excitedly.
"Look Jack," she says, "there's this cruise tomorrow that is on sale! Only $500!"
"I'm really not into cruises, to be honest." Replies Jack. "Here's $500, why don't you go and have a good time?"
She agrees to do just so, and as it turns out, both his wife and his mistress ended up going on the same cruise.
A few days later, his wife comes back from the cruise. As she tells him how much fun she had, she shows him photos she took. While looking them over, Jack notices that his lover Brenda is in some of the photos in the background. He points to her and asks his wife: "Who's she?"
"Oh, her." sniffs his wife disdainfully, "I call her the cruise-slut because she slept with half of the men there."
The next day, Jack goes to the office and gets the same excited story accompanied by photos from his mistress Brenda. Once again, he sees a familiar face in some of the photos - his wife. He then points to his wife and asks Brenda: "Who is she?"
"Oh, her!" says Brenda, "She's such a nice woman, with all the men on board, she never left her husband's side for a second!"