Hitching a Ride

A guy driving a pickup truck in the middle of nowhere picks up a hitch-hiker. It gets dark and the hitch-hiker falls asleep. Suddenly bang, and the hitch-hiker wakes up.
“What the hell was that?” he asks shaken.
The truck driver replies, “Ehh, just some kinda animal, go back to sleep.”
Further the same thing again, bang, “What the hell was that?”, “some kinda animal again.”
Further into the night, the hitch-hiker wakes up to bang, bang, bang.
“What the hell was that?”
“One of my wife’s lovers!”
“How terrible,” says the hitch-hiker, “but there were 3 bangs.”
The truck driver replies, “Yeah, well I had to go through two fences to get the bastard!”