Case in point: when I was younger and played soccer, we had one ref who before the game would go over rules with us. Invariably, he'd ask us what offsides was. A younger kid would always give him the book answer for the league: being ahead of the ball with less than two defenders between you and the goal (goalie counts as one). He'd quickly then say "no! offsides is this." and point to his whistle. The point was very clear... He had the final call on what was offsides, so there was no use complaining if we had a different opinion.

He was actually a quite fair ref.