When your guests misbehave

First of all, I must say:
It is not your fault if your own guests misbehave at a restaurant. Unfortunately, we cannot be responsible for adults' actions.

Here is the setting:
The host invited a group of about 10 to have dinner at a friend's restaurant. She planned it with care and made sure all guests' needs could be met during dinner. One of the guests decided to invite 2 friends to attend as well. The hostess welcomed the additional guests, 2 ladies.
The restaurant: a Colombian owned restaurant, specializing in South-American cuisine, featuring Colombian music, decor and on that specific evening, also a late Karaoke entertainment event.
The guests: Some were of Hispanic descent and some were not. The 2 additional guests spoke English and no Spanish, and were not familiar with Colombian cuisine, atmosphere and the "Latin touch".

What happened:
Upon arrival (a rather late arrival), the 2 ladies approach the table, greet everybody, and start giggling and whispering to one another. After taking their seats, they decide to use the table's paper napkins to write notes and pass it around the table to some people (No, the ladies were not young teenagers. They could have been teenagers' mothers maybe). The hostess spots the behavior and actually gets to read one of the notes. It said: "WTF, all Spanish here?!"

The response:
The hostess felt embarrassed and very uncomfortable. The table was displaying a large amount of handwritten notes on paper napkins, and even the owner, once approaching the table to greet the guests, noticed the pile of written communication laying around.
The hostess made sure the 2 ladies had a menu with English translation and asked if they needed any suggestions. She tried accommodating their needs but their behavior was getting her really, really upset and embarrassed. She even apologized to her friend, the restaurant's owner.

My response:
A few days later, after hearing about the incident, I felt bad. It is so sad that adults can behave in such manner. I immediately told her "It is not your fault!. You can only feel sorry for them, as the event has passed and they ended up leaving a very bad impression on you, on the restaurant staff and other guests at the table."
What would you do in such a situation?
I would keep in mind they are my guests, but I would also keep in mind they are probably embarrassing themselves and others. The most appropriate response to this situation would be to address them, engage them in conversation, ASK them questions and offer help. Deviating their attention from their own actions could change their focus. If they see you reading one of the notes, you can diplomatically make a comment like "Oh, this must be your first time here! We admire the quality of service and of the food they serve. It's a great way to learn more about the Colombian culture. They are wonderful people!" Smile when you say that, be sincere, not snippy, and look them in the eyes. Your goal is to appease the situation, and not make it worse for anybody. You are the hostess, and as a hostess, sometimes, we have to deal with guests who misbehave. Unfortunately.

No matter what, always be a class-act!