A man and wife are invited to a Halloween party. But at the last minute the wife complains of a severe headache and cannot go. The husband pleads to stay with her, but she says the headache wasn't that serious, so he reluctantly leaves without her. The wife goes to bed and falls asleep.
An hour later she wakes up feeling perfectly fine, so she decides to see what her husband will do at the party without her. He won't know what her costume is after all.
The minute she arrives she sees him, making out with every good-looking chick he sees. Angered, she sidles up to him, and, being a very seductive babe herself, her husband leaves his partner for some new "action". They make out for awhile, then he whispers a proposition in her ear and she accepts (he is her husband, after all). So the two go behind the garbage cans in the parking lot and have a little bang.
Wanting to leave before her husband, she leaves her partner and arrives home at midnight. Then she waits for her husband to explain himself.
He arrives home an hour later. "So dear," she asks him, "how was the party?"
"Terrible," replies he, "It always is without you at these things. I didn't even dance, just played poker with Bill in the den."
"Yeah, but the guy who borrowed my costume had one helluva time!"