I'm not condoning any of the following, but: - you don't bring liquids to an airport - you don't go to Thailand to insult the king - you don't bring chewing gum to Singapore - you don't fly via the US due to the TSA - you don't overstay your visa
The point is, if you want to stop unwanted behaviors, you make rules and you enforce them, and eventually (most) people, even those that haven't been to your country, will know what isn't condoned and modify their behavior accordingly or stay away.