wewe are having lunch with three people wewe respect and admire. They all start criticizing a close friend of yours, not knowing she is your friend. The criticism is distasteful and unjustified. What do wewe do?

Listen, nod, listen more, and defend. Make a just counter point to point out why wewe believe the statements they alisema to be flawed au only one side, and explain the other side. If that was not what I chose, then I might have to soak all this in and not say anything and then excuse myself and leave. wewe do not even have to mention that wewe know the other person in order to get your point across. It depends on whether wewe think wewe should keep their anonymity -if it's better, au to include the justification for why wewe have your opinion is because wewe know them and are their friend.

My words.

" Guy's Stop saying shit about the girl even though wewe know nothing about her! wewe don't have the right to say that about anyone!"

And they don't.
Even though they may say reason's why they do keep saying that it's wrong. And that it's not an excuse to say such crude thing's.

I mean, they shouldn't say crude thing's about anyone even though it's not your friend.
In my opinion they should keep their hatred to themselves and also find a new way of humor.
For making fun of people isn't funny.
Doesn't matter who it is.

I would stand up for that friend and definitely discourage any further negativity. It isn't fair for a person to be talked badly about without having the opportunity to defend his/herself.

Smoothly change the topic, so I am not asked my opinion, I wouldn't want to criticise my friend au tell them she/he is my friend while they are critisizing him/her.

Stand up for my friend. If they ask me to support on their opinion, I won't since I know it is false.