One thing that generally bugs me about fantasy games is that the classes are not imposed at all in the rules. People always like to talk tough but when push comes to shove, rank actualy has bearing and meaning.

Talking 'smack' is one thing. But when confronted with a person of higher status, both in the real world and I feel in game, there is an effect. The idea of consequences will occur. If I am beligerant to this person, it could bite me in the ass. If I am offensive and aggressive to this person...bad things could very much happen.

Anyway, Warhammer has a nice simple class system. Street, Mercentile and Noblility. It seems easy enough to institute a bonus/negative for social situations.

My thoughts are:

When dealing with a higher class, add one Misfortune dice per rank higher. When dealing with a lower class, add one Fortune dice per rank lower.

So a Street character (pretty much most of the players) trying to accuse a Noble of Chaos involvement in a public setting would gain 2 Misfortune dice.

Furthermore, when dealing with the higher class, I would like to institute a Stress penality. I'm not sure how to go about this. It would be simiilar to the Fear faction that's in the game. I've no problems if the players want to run around accusing people of higher station of chaos, but I want them to understand that there is still an inheriant social awkwardness and dread to it all. You're born into this world probably being told that nobles are better than you (in all ways). So to start dealing with them sociality should be a nervious affair.

Adding or <P> to social encounters due to status seems perfectly reasonable to me.

You should probably further modify the encounter my setting as well. As a visitor, the party'd be hard pressed to find a sympathetic ear for their "mad ravings".

Check out the throne room card for social rules simialr to this

If you want to bring stress into such social situations, why not actually bring fear into it. If a character who is judged to be from the STREET wants to accuse a noble of being a chaos cultist, then make that noble have a FEAR 2 rating for the encounter. That would make the class system seem more real. How you fit characters into the three classes, if at all, may depend on how they look and act.