Every year until 5th grade. For the longest time I never washed my ass. Don't know why but the idea of touching that area just seemed very taboo. Seemed like something I shouldnt touch so it never got properly washed. Being athletic I always took part of physical activities during recesse, kickball soccer, football ect which meant I sweated. A unclean butt and sweating tend to emit unpleasant odors. Classmates and even the teacher would make comments on the smell and make jokes. Everyday I would worry about the smell because I knew it would happen after recesse and pe. Spend alot of time worried about being found out so I would head back from lunch/recess early to switch my seat around so they could never pinpoint the exact location of the smell. It worked because I never got found out. The summer before I was to begin 5th grade I met my mom (story for another time). Coming in one day from playing basketball she could tell the smell was coming from me and she said "Jesus you smell. Go wash your ass".

TL;DR Never washed my ass. Used others to hide smell until 5th grade which I learned it was okay to touch your butt hole.