My strange urban legend:p

Welppp... I am not really that sure what an "urban legend" is but, I feel like I know a lot of them... I'll just take a jab at it anyways!! I heard this one story from my brother when I was younger and it was about a little boy at the dentist. The little boy was sitting in the dentist chair and he had to receive the laughing gas stuff... Well when he was "under" the little boys dentist was a mass murderer. He took the little boy and sowed his eye lids shut and his mouth. When the little boy woke up... he started to scream, but it was muffled. His mouth was sowed shut... The dentist told the little boys mother that the surgery is lasting longer than he thought so it'd be an hour or so more. The dentist walked back in the room and saw the little boy trying to cut the thread off his mouth, but he couldn't see. The dentist snapped... and threw the little boy out of the window... from the 4th floor of the building... I'm pretty sure my brother only said that, because I was going to the dentist the next day and he was trying to scare me. It definitely worked!! I made sure my mom went into the room with me when the dentist was in the room with me. I told my mom why I wanted her to be in the room with me, and she grounded my brother. She was really mad lol...