The farmer lent the boy his gun, telling him not to kill any farm animals.
The city boy headed off and soon after saw a goat. He managed to creep into range and finally shot it. Not knowing anything about animals, the boy didn't know what he'd killed so he ran to the farmhouse and described his kill to the farmer.
"It had two saggy tits, a beard, a hard head and it really smelled rotten!" said the boy.
"Oh, shit!" said the farmer.
Spoiler:
