Kids Acting Out in Public

When you take to twin boys to the post office and one starts going up under the tables and the other one wants to touch everything and then start hitting the other one what do you do?  That was my dilemma to with Nick & Nate, Nick wanted to get under the table and Nate wanted to touch everything, so I picked Nick up and held him because he is the smallest and he asked and then Nate wanted to be held and sit up on the counter when I told him he couldn't he got worse.  I had to put both of them down and pay for my money order and that's when Nick started passing licks and I told him to stop and he keeps on of course the postal worked started talking to him she says some times you have to distract them, on the way out Nate wanted some candy I had bought them Chick-fil-A ice cream before we got there so they had ice cream in the car, that what I told him why he started dropping to the ground screaming like I had killed him so I told Nick to get down and I picked up Nate and told Nick to come on then he wanted to stay on the ground I had to pick both of them up and carry them to the car while people were looking at me while they were screaming like I had done something.  I don't like being embarrassed by kids, I couldn't beat their butts like I really wanted too.  So what do you do, how do you deal with the foolishness?