http://abc.go.com/primetime/supernanny/toptenrules.html

The Nanny on that show actually does a really good job of disciplining children without resorting to yelling or physical punishment.

If a child is spoiled rotten and they want their way all the time, just lay down ground rules and stick with it. If the kid doesn't get their way and starts bawling, tell them to stop that or else they're gonna get a time out (or something similar. Super Nanny uses the naughty chair). If they continue to do something bad, you put them on a time out and leave them there for a set amount of time or until they stop crying or apologize or whatever. If they move away from the spot, you take them right back and tell them not to move. They do it again, you take them right back. Over and over again until they get it into their heads that this punishment won't go away until they accept it and sit there for as long as you said they would have to sit there.

You need to be stern with little kids because if you relent, they'll know that they can get whatever they want just by screaming. Don't yield to the kid just for the sake of peace and quiet or because it's easier to give the kid what he wants.

Be firm. Follow through on the punishments. Don't get angry or yell. That just makes things worse.

All these things the parents should be doing. Perhaps you can direct them to ABC so they can watch Super Nanny. It really is an informative show.