How funny you posted this reply. My 18 yr old daughter (yes, blond) locked her keys in her car two times in two days. That is exactly what her mother told her.
She can't use her car for one week, except for school. She also got an additional assignment from me. She has to get three estimates (two locksmiths and one towing company) for coming out to unlock the car.
The combined cost of the three is what she has to give up as part of her punishment. She also has to get three additional keys made and buy a "Hide-a-key" for her car. One key is hidden in her purse and one is for one of her friends.