A caterer who is also a friend went to pick up the wedding cake for my daughter's wedding. It was a hot April day! The cake was placed in the trunk of her car; she also laid her purse in the trunk. Well, she (or somebody else) closed the trunk lid. Then she realized that her car keys were in her purse in the locked car in the hot sun!
She tried to call her DH but no luck. Various men tried to remove the car's back seat as the sun got hotter. Then a passer-by, who had the same model car as hers, tried his key. Voila! His key unlocked her trunk.
(Makes you wonder how safe locked cars are!)