I shot my neighbor in the back with a bb gun while he was on a riding lawn mower.
When I was young I would injure kids/friends constantly due to my rough housing and bigger size. This probably helped me become semi decent at making people laugh. Cause I would try and calm them down (stop crying) before they went and told the teacher (worked most of the times).
In junior high, I tripped a mentally challenged kid during recess (was last year of that) by putting my foot and pressing on the back of his knee, I knew he was probably going to fall over but assumed that he would catch himself, he tumbled over and a decent size crowd found out that it was me and threatened to beat me up if I didn't apologize. I of course apologized and he hugged me afterwards in front of everyone. Everyone then teased me that I was hugged.
Also in junior high I would go around during lunch and stick food under people's chair for them to sit on. Usually I'd wait for them to lift up a little out of their seat (if they were reaching for something on table or get out of seat) then I would stick food on their chair. My favorite was getting people to sit on the crappy hamburgers.
During high school years I was the driver for a heist of VCRs (before DVDs were mainstream) from a hotel. While this might not be seen as mean, my actions (along with the other people involved) probably prevented a few people from being able to pleasure themselves to a porn at a hotel/interrupted them in the process.
I'm sure I've done some other mean things perhaps 10x as bad as the ones I listed. However, I can't think of them at this moment. I usually try and treat people nice.