"Gorilla at the zoo getting turned on" joke

It's a beautiful, warm spring morning and a man and his wife are spending the day at the zoo.
She's wearing a cute, loose-fitting, pink spring dress, sleeveless with straps.
He's wearing his normal jeans and a T-shirt. The zoo is not very busy this morning. As they walk through the ape exhibit, they pass in front of a very large hairy gorilla.
Noticing the girl, the gorilla goes ape. (no pun intended.)
He jumps up on the bars, and holding on with one hand (and 2 feet), he grunts and pounds his chest with his free hand. He is obviously excited at the pretty lady in the wavy dress.
The husband, noticing the excitement, thinks this is funny. He suggests that his wife teases the poor fellow some more.
The husband suggests she pucker her lips, wiggle her bottom at him, and play along.
Shedoes, and Mr. Gorilla gets even more excited, making noises that would wake the dead. Then the husband suggests that she let one of her straps fall to show a little more skin.
She does, and Mr. Gorilla is about to tear the bars down.
"Now try lifting your dress up your thighs and sort of fan it at him." he says... this drives the gorilla absolutely crazy and now he's doing flips.
Then the husband nabs his wife by the hair, rips open the door to the cage, slings her in with the gorilla and slams the cage door shut. "Now, tell HIM you have a headache."