Making A Parenting Skill Roll

How, as a parent and Game Master, does one deal with your children as players? What do you do when Phillip pinches Emily and she fireballs Phillip's character in retaliation? Here are some suggestions:

• GM: "Until you learn some manners, you have a -5 modifier to ALL rolls!"
  --Michael S. Webster
• GM: "You are suddenly teleported to your room where you will sit until the rest of the group is fourth level."
  --trevanem
• GM: "I'm taking away your +5 Holy Avenger until you learn to play nice!"
  --Michael S. Webster