An old woman walked into an antique store and looked at a diamond necklace in a glass cabinet.
Suddenly, she let out a fart (she polluted the air). She coughed, trying to disguise it, because a shop assistant was walking by.
She then called the assistant over and asked how much the necklace was.
The assistant replied, "If you just farted looking at it, you'll shit yourself when I tell you the price!"