Thank You for Saving My Life

A very rich grandma wanted to check how much is she loved by her three grandsons. So, she took a walk with the oldest and faked that she tripped and fell into the river. The grandson immediately jumps after her and pulls her away from the river flow. The very next day he sees a brand new BMW in front of the house with a note attached to the windshield. The note said: Thank you for saving my life! Your grandma The next day she repeated her acting with her second grandson. She fell into the river and her grandson saved her as well. He also got a new BMW the next day with the same note. Grandma was all excited about her two grandsons - but she still had one more to test. So she went for a walk with her youngest grandson, fell into the river, but the grandson didn't budge. He continued his walk and went back home. The very next day he saw a brand new Mercedes in front of his house with a note: Thank you for saving me! Your grandfather