Swiped from a friend, this might be an old one, but...
Tight Fit
A man went to a urologist and told him that he was having a problem and that he was unable to get his penis erect. After a complete exam the doctor told the man that the muscles around the base of his penis were damaged from a prior viral infection and there was nothing he could do for him.
However, he knew of an experimental treatment that might work, if he were willing to take the risk. The treatment consisted of implanting muscle tissue from an elephant's trunk in the man's penis.
The man thought about it for a while. The thought of going through life without ever experiencing sex again was just too much for him to bear. So, with the assurance that there would be no cruelty or adverse effect on the elephant, the man decided to go for it. A few weeks after the operation, he was given the green light to use his newly renovated equipment.
As a result, he planned a romantic evening with his girlfriend and took her to one of the nicest restaurants in the city. However, in the middle of dinner he felt a stirring between his legs that continued to the point of being extremely painful. To release the pressure, he unzipped his fly and immediately his penis sprang from his pants, went to the top of the table, grabbed a roll, then returned to his pants.
His girlfriend was stunned at first, but then with a sly smile on her face said: "That was incredible. Can you do that again?"
With his eyes watering, he replied: "I think I can, but I'm not sure if I can fit another roll up my arse."
