Archaeologist.
A young archaeologist gets a job on a dig in the Middle East. He flies out there and is met by an older archaeologist, who shows the young man around the dig.
"You'll like it here," says the older man. "On Friday evenings, we have a lorry-load of beautiful girls sent up from the village, and we all have an orgy."
The younger man blushes, and clears his throat.
"Er, look, sorry," he says, "if you don't mind, I'll give that a miss."
"Oh, all right then," says the older man. "Well, on Saturday evenings, we have a lorry-load of beer sent in, and we all get drunk."
The young man colours up again, and he says, "Sorry, but that's really not my scene."
"What's the matter with you?" says the older man. "You don't like women, you don't drink. Are you gay, or what?"
"I'm certainly not!" retorts the young man, angrily.
"Oh, right," says the older man. "Well, you won't like Sunday's party either, will you?"