What do you do? Do you spank them? Do you yell and threaten? Does somebody get a time out? And if so, is the time out for you or them?
Ideally I try to avoid spankings or resorting to yelling and threats. "Try" being the key word here. I usually try giving time outs in the corner, one minute for each year of their age, or when I stop being side tracked by the other kids and remember that there is a child in time out. Then I make them tell me why they are in time out and I make sure to explain why their behavior is unacceptable. Then we end with apologies and hugs.
Now by dinner time my patience is getting very worn and after what feels like fifty thousand time outs between three kids and at least one time out for mommy, which consist of hiding in the bathroom, I do sometimes resort to yelling and threats of a spanking.
Most days I can manage without spanking somebodies butt but certain offenses are almost guaranteed to get a sore rear end. Doing something that can actually cause harm to themselves or each other, usually ends in a spanking.
I know a lot of people look down on parents who choose to spank their kids but there is a difference between spanking and beating. I think some people tend to forget that. I had my butt blistered a few times when I was a child and it didn't turn me into a mass murder or anything. I think that as long as you use spanking as a last resort, you don't get carried away with it, and you make sure that your child understands that you still love them, there is nothing wrong with using it as a discipline method.