The
driver was at the petrol station to fill his car up. In the shop, he
was paying the lady when a stranger got into his car discreetly.
After that the driver left the station and looked in the mirror and
he saw the stranger in the back seat.
The
driver was thrilled.
The
stranger had a bag full of money and a gun. Maybe / perhaps he
held-up a bank ( he robbed a bank), or maybe he stole the money in a
shop.
After
that, he stopped the car, and the stranger got out of the car, and
menaced (= threatened) the driver. He was sadistic and made the
driver beg and cry.
But in the end, we discover that it was a joke. The singer invented everything.