While I agree with Frank, I think you also have to clearly state expectations that you want kids to be nice, and this sometimes involves discipline. Though I have not always agreed with my MIL, the best advice she ever gave me when I became a parent was to say that she always wanted her kids to be welcome everywhere - for people to be glad to see them. As a former teacher, I could relate to that - thinking of those students I was always happy to see walk into my classroom vs. the ones I couldn't help but dread. What a tremendous gift to give your kids.
2. I think we use the word "discipline" instead of...
...using the actual word which is "punishment".
In my view discipline is a taught value that is learned through example. If a parent is disciplined then they are tolerant, patient, They let others speak without interrupting them, and show a calm demeanor that is not self centered with want.
How many undisciplined (rude, interrupting, self centered, etc...) parents have you encountered with out of control kids? Where did the kids get that...hummm I wonder...and this is where parents say they must "discipline" their children when they really meant to say they need to "punish" their children (time out, restrictions, spanking, etc...).
Which in turn sets in motion all kinds of contradicting messages both mentally and emotionally in a child. It screws them up.