I'm the youngest of three brothers. We were each born about four years apart. When I was about thirteen the oldest brother came home from college and I was real happy to see him. I thought I'd celebrate by showing him something the middle brother had shown me.
We lived in a split-level home. My oldest brother came in and went downstairs to the den and sat down. I grabbed a book of matches, ran downstairs, did a baseball slide on the floor and started to roll backwards with my keester sticking straight up in the air. I struck a match, lit a fart, and then I sat up laughing just like the Beavis and Butthead type I truly was. However, instead of laughing, my brother looked like he could kill me.
"I want you to turn around and apologize to her right now!", he yelled. Uh oh! I turned and looked at the corner behind the stairs and there sat a girl he had brought home to meet the family. I've never seen such a confused, disgusted look on anyone's face before or since.
Well, now she's my sister-in-law of over thirty years and we still laugh about it from time to time.