If you're going to the States, there are four things you should never do:
1) forget to tip at least 15% at bars, restaurants etc.
2) discuss race, skin colour, or gender issues
3) discuss religion
4) discuss political views. These hold true for dinner as well - if friends ask you for dinner, do not start a conversation on these subjects. They'll most likely think you rude.
If you're going to the Netherlands:
Yes, the drugs, euthanasia and abortion laws are probably tolerant, compared to yours. Most of us are very happy they are, and most of us do not appreciate derisive comments or lame jokes about these laws. For example (and I've heard all of these...
1) The Dutch are not on drugs all the time.
2) You cannot come to the Netherlands to get your mother in law killed.
3) Our laws do not mean that anything goes when it comes to ethics.
4) We aren't actually backwards at all. We have electricity, fridges, broadband internet and iPhones just like you do.
So... if you do not agree with our laws, please just do not discuss these subjects. Just enjoy the cheese, windmills, paintings and tulips; and I'll be happy to give you a tour