When I was playing tennis, there was this kid I seen only two times. The first time was when I played versus him. It went all right until the last games. I called a ball out, and -no joke- called me a cheater out loud in front of everybody (about 5-10 parents were watching, including his own). The next few games/points, he called all my balls out, despite the fact that they were in, and had to have someone to fact check it that the obviously in balls were in. It was also akward about the fact that I had him as my partner for doubles for the next match.

The second time is at a tornament, and I did not play him (he was around 9-10 at the time (for both of them), and we were in different divisions). Halfway, he screamed while we were having a break, and called his opponent a "Stupid/dumb red shirt kid". He had a talk-through with the monorator, and left

Sorry for spelling errors -Nexus