There is a team close to me recently that was trying to get a late-season recruit from far away qualified for playoffs in the last match of the season. Except the player couldn't make that last match, so this team literally pulled a guy off the street to play and they tried to pass him off as this player they were trying to qualify for playoffs. Except this player barely knew the rules of tennis and couldn't hit the ball at all. So the other team knew something was up and filed a complaint. The team captain and the player's doubles partner were suspended from USTA play for a year, and everyone else who knew about this scheme were suspended for 3 months.
I also know of someone who completely annihilated his racket during a match. The other team filed a complaint, and the player was suspended for 3 months. I've come very close to doing that, I better watch myself, lol.