I truly despise these situations. I get rowdy and loud, but never BOO unless it's an extremely clearly bad call, or if it looks unfair. I try not to be negative to anything, even opposing teams.
If I have my kids with me, I will probably just frown and tilt my head while looking at them, and make a pointing motion to my kids, and they'll say "Oh, ok... ok... I'll tone it down, sorry about that" because they see my kids are there, but... they will think I'm an ahole because I ask nicely to stop cursing so much.
I guess I need my kids with me at all times?