I've never had outright forfeits in high school in the 5 or so years I've been working. I've had cancellations or teams drop out of leagues (thus losing my games) before.
I've had a number of weird situations before with teams not showing up or things like that:
ONE
One time I showed up for a JV boys game about 30 minutes before game time. I noticed that the lights at the gym were off and no one was home. This rang a bell but I figured sometimes people open the gym late. Alas, it wasn't meant to me. I waited around for a while and no showed up. Interestingly, one of the VARSITY officials showed up as well. I guess he didn't know either. However, I noted that neither one of our partners ever showed up. STRANGE.....BTW this was the AD/Coach's fault. THe game was moved to the opponents gym (different city, different association).
TWO
This situation involved the same school as above. I was schedule for a JV boys game at 5 PM. I showed up about 4:40 PM and my partner is already there. My partner has interesting news. The opposing squad had decided earlier in the day to not bring their JV squad. So the school was ok with it....BUT did not tell the assignor.
So here we are at 5 PM with the varsity squads ready to play. In most circumstances, my partner and I would have reffed it. However, the opposing squad was a very good local team and I guess the assignor wanted a more veteran crew on the game.
So, everyone waited until about 6 PM and then the varsity game finally played.
Odd stuff us refs have to go through....