A man went to the doctor and asked "How can I improve my sexual performance?" to which the doctor replied "Well, if you masturbate before sex you will last longer during the act."
The man was glad to find an answer and thought about it all of the next day but he found trouble finding a suitable place to do it. He couldn't do it in his office, the toilets had been flooded that day and an alley nearby was too unsafe. On his way home he had an idea and pulled over in his truck on the motorway. He crawled underneath as if he was examining it. Satisfied with the privacy he closed his eyes and undid his belt. He pulled down his trousers and started to masturbate, he grew close to his orgasm but felt a tug at his trouser leg. He kept his eyes shut not wanting to ruin his climax asked
"What?"
"What on earth are you doing?" asked the cop.
"I'm checking the rear axle, its fucked!" Replied the man.
"Well you better check your brakes too, your truck rolled down the hill five minutes ago!"