A blond go into parachute shop She come to the cashier and ask him how to use the parachute, he then explain to her that after she jump, she need to pull the yellow string. She ask him ""But what if i will pull it and the parachute won't open?"". He then explain her that this is a special parachute with backup, and if the yellow string won't open the parachute, then she need to pull the red string to open the second parachute. So then the blond ask him, but what if I will pull the red string but the parachute won't open? So the cashier tell her to come the next day and he will give her a refund.