the Old Lady

One day an old lady is walking down the street, dragging two large, plastic garbage bags with her, one in each hand.
Unfortunately, there's a rip in one of the bags, and every once in a while a $20 bill falls out onto the pavement.
Noticing this, a policeman stops her.
"Ma'am, there are $20 bills falling out of your bag.."
"Oh darn! says the little old lady.
"I'd better go back and see if I can collect them. Thanks for the warning."
"Well, now not so fast", says the cop "how did you get all that money? You didn't steal it, did you?"
"Oh no" says the little old lady.
"You see, my back yard is right next to the football stadium. Each time there is a game, a lot of fans come and pee through the bushes; right in my flower beds! So I go and stand behind the bushes with a big hedge clipper, and each time someone sticks his willie thru the bushes, I say $20 or off it comes.
"Well, that seems only fair" laughs the cop. "O.K., good luck!
By the wasy what's in the other bag?
"Well " says the little old lady, "not everbody pays."