It's not good to mess with us Old Guys.

An older gentleman had an appointment to see the urologist who shared offices with several other doctors. The waiting room was filled with patients. As he approached the receptionist’s desk, he noticed that the receptionist was a large unfriendly woman who looked like a Sumo wrestler. He gave her his name.
In a very loud voice, the receptionist said, “YES, I HAVE YOUR NAME HERE. YOU WANT TO SEE THE DOCTOR ABOUT IMPOTENCE, RIGHT?”
All the patients in the waiting room snapped their heads around to look at the very embarrassed man. He recovered quickly, and in an equally loud voice replied, ‘NO, I’VE COME TO INQUIRE ABOUT A SEX CHANGE OPERATION, BUT I DON’T WANT THE SAME DOCTOR THAT DID YOURS. The room erupted in applause!

Warning! Only to be read with empty bladder!

Don’t mess with old people (especially little old ladies):
A little old lady was walking down the street dragging two large plastic garbage bags behind her. One of the bags was ripped and every once in a while a $20 fell out onto the sidewalk.
Noticing this, a policeman stopped her, and said, “Ma’am, there are $20 bills falling out of that bag.”
“Oh really? Darn it!” said the little old lady. “I’d better go back and see if I can find them. Thanks for telling me officer.”
Well, now, not so fast,” said the cop. Where did you get all that money? You didn’t steal it, did you?”
“Oh, no, no, nothing like that”, said the old lady. “You see, my back yard is right next to the football stadium parking lot. On game days, a lot of fans come and pee through a knot hole in the fence, right into my flower garden.
It used to really tick me off. Kills the flowers, you know. Then I thought, ‘why not make the best of it?’ So, now, on game days, I stand behind the fence by the knot hole, real quiet, with my hedge clippers….
Every time some guy sticks his thingy through my fence, I surprise him, I grab hold of it and say, ‘O.K., buddy! Give me $20, or off it comes.’
“Well, that seems only fair,” said the cop, laughing. “OK. Good luck! Oh, by the way, what’s in the other bag?”
“Well, you know how it is in business”, said the little old lady, “not everybody pays.”