When speaking openly with a group of people, is it okay to speak casually with some and formally with others?

Question

Say that I'm having lunch with my buddy outside, and my boss comes over and starts talking to me. Obviously, with my boss, I'll talk with proper keigo and stuff. But in front of my boss, am I allowed to talk directly to my buddy with full-blown tameguchi, or is that considered impolite?

For example, say my buddy was teasing me in front of my boss with something like "____は相変わらず不器用ですか" ("Is _____ still clumsy as always?"). Am I allowed to retort at my buddy with things like "何いってんだお前" (the hell you on about) and "うっせお前" (shut your ass), or would it be considered rude to talk like that in front of my boss, even if the language isn't directed at my boss?

Answer 1

In such a situation, it's basically okay to use casual language with your friends, but if your boss is listening, you probably don't want to say anything too dirty or slangy (of course, the same is true when you're talking in English). In your specific case, うっせお前 would be considered a short tsukkomi, so it is more likely to be tolerated, but in general, adults may temporarily refrain from using お前. If there is a really important person or if you are attending a very formal ceremony, it is not strange for friends to begin speaking to each other in keigo.

Answer 2

I agree with @naruto. The general rule is that you continue using the language appropriate for each (so you use tameguchi to your buddies but keigo to your boss).

Additionally, there is a special rule in which when you are talking to a customer, you must omit keigo for your boss (because now you are interacting with your customer as a single group with your boss).

For example, you say 部長は席におられませんでした and 部長はこうおっしゃっていました when you talk with your colleague or your 課長. However, if you are talking to a customer you have to say 部長は席におりません and 部長はこう申しておりました. However you still don't use tameguchi to your boss even in that situation (so you should still say です・ます to your boss in front of your customer). Just when you describe what your 部長 did etc. to your customer, you refrain from honouring your boss.