A zoo had among its animals a female gorilla, whose mood was becoming increasingly difficult. The vet concluded that she was on heat and that a mate should be found. The vet contacted some other nearby zoos to find a partner for the broody female, but to no avail. The female gorilla's behavior continued to worsen, but the vet noticed that she grew calmer, and strangely responsive, whenever a particularly well-built and none-too-handsome keeper entered the enclosure. Being an unprincipled and adventurous fellow, the vet put an outrageous proposition to the keeper: For a fee of five hundred bucks would the keeper consider spending a little 'quality time' with the gorilla, purely in the interests of research of course?....
The keeper, also an unprincipled and adventurous fellow, pondered the suggestion, and after a few minutes agreed to the offer, subject to three conditions. The vet, intrigued, listened to the keeper's demands:
"First," the keeper said, "No kissing."
"Fine," said the vet.
"Second, no-one must ever know - if this gets out I'll kill you."
"You have my word," said the vet, "And your final condition?"
"It's just," said the keeper a little awkwardly, "Can I have a couple of weeks to raise the five hundred bucks?"