Usually I think I am saying it under my breath but in actuality everyone hears it
I did this once this year. End of the game, fourth down, needing 10 for the first down, but 80 for the game winning score -- the team lines up in a FUBAR formation. On my side, there's a man in no mans land who runs down field -- unfortunately, he's either an illegal man downfield or the 5th in the backfield. They complete the pass for 30 yards, but it comes back on the penalty (I called him "on", so it was illegal downfield).
After the play, a parent in the stands yells "You can't always beat the refs!". I said, out loud, I'm sure some of the coaches heard, "I love my job".
None of the coaches complained about the call though. So they seemed to understand that things were not kosher on the play.