Old joke though still funny...
 

Costume Party -- HAPPY HALLOWEEN!!

A couple was invited to a swanky costume party. The Mrs. got a terrible
headache and told her husband to go to the party alone. He being a devoted
husband protested, but she argued and said she was going to take some
aspirin and go to bed and there was no need for his good time being spoiled
by not going. So he took his costume and away he went.. The wife, after
sleeping soundly for about an hour, awakened without pain and, as it was
still early, decided to go the party. Since her husband did not know what
her costume was, she thought she would have some fun by watching her husband
to see how he acted when she was not with him. She joined the party and soon
spotted her husband cavorting around on the dance floor, dancing with every
nice woman he could, and copping a little feel here and a little kiss there.
His wife sidled up to him and being a rather seductive babe herself, he left
his current partner high and dry and devoted his time to the new babe that
had just arrived. She let him go as far as he wished,naturally, since he was
her husband. Finally, he whispered a little proposition in her ear and she
agreed.

So off they went to one of the cars and had a quickie. Just before unmasking
at midnight, she slipped away, went home, put the costume away and got into
bed, wondering what kind of explanation he would make for his behavior. She
was sitting up reading when he came in, and she asked what kind of a time he
had. He said: "Oh, the same old thing. You know I never have a good time
when you're not there." - "Did you dance much ?" - "I'll tell you, I never
even danced one dance.. When I got there, I met Pete, Bill Brown and some
other guys, so we went into the den and played poker all evening. But you're
not going to believe what happened to the guy I loaned my costume to...."