Two young guys were picked up by the cops for smoking dope and appeared in court before the judge.  The judge said "You seem like nice young men and I'd like to give you a second chance rather than jail time.  I want you to go out this weekend and try to show others the evils of drug use and get them to give up drugs forever. I'll see you back in court Monday."

Monday the two guys were in court and the judge said to the first one "How did you do over the weekend?" "Well your honor I persuaded 17 people to give up drugs forever." "17 people? That's wonderful. What did you tell them?" "I used a diagram your honor. I drew two circles, the first a small
one and the second a much larger one, and I told them that the big circle is your brain before drugs and the small circle is your brain after drugs." "That's admirable" said the judge..

The judge turned to the second boy and said, "And you, how did you do?"

"Well your honor I persuaded 156 people to give up drugs forever." "156 people! That's amazing! How did you manage to do that!" "Well I used a similar approach, also drawing two circles, one larger than the other. While pointing to the smaller of the two circles... he said, "this is your asshole before prison....."