Sometimes a Japanese person will say to me:

> そんあに丁寧な言葉を使わなくても言いんですよ。

This is an invitation to be less formal. But how much less formal? As I have experienced, sometimes [unintentional gaffes][1] can be committed blithely as one learns to navigate the treacherous waters of the politeness hierarchy. Note that the expression itself uses です even though it is a request to use less formal speech, and that is the level of politeness  I would normally be using. So I find the whole matter confusing. The eternal politeness dance ...

Now, here's the catch: I feel it would be rude to ask something like "What level of politeness do you suggest I use?" That might come off as sarcastic or, worse, a rebuke. Any advice?


  [1]: http://japanese.stackexchange.com/questions/94/how-rude-is-it-to-say