The stranger gets in and he realized that there is a monkey in the back seat of the car. Twenty minutes goes by and suddenly the driver reaches back and slaps the monkey in the head real hard. The monkey then jumps in the fron seat and starts giving the driver a blow job.

Again twenty minutes later the driver does this again, and the monkey performs the same action.

After a few other times, the driver asks the stranger "Do you want to try?" and the stranger replies, "OK but don't slap me that hard!"