Some parents are right pricks. I've encountered my fair share. One parent even argued with me when I sent off his son who clearly called me a ****.
I sent two off in the final 20 seconds of a game once.
One called me a ****ing ******. Then as I was about to signal for the restart, his mate called me it right next to me!
Two reds, and the parents had the cheek to charge on at full time to confront me.
Received full apology from the manager and chairman by phone. The chairman was particularly unhappy as they were a community club who were associated with the local disabled association. The club actually banned parents from attending the final three games as no one owned up. My mate had one of their games and told me there were no supporters present from that club.