In general, I use British words when talking to Amy, but there are a couple I'm unsure about...
Specifically, for a male hen, whether to use "cock" or "rooster", and for the implement you use to remove pencil marks, whether to use "rubber" or "eraser". In each case, I think the first word of each pair is more British, but it has an undesirable slang meaning in the States, so I'm not sure whether it would be a good idea to learn that word, only to be laughed at later. (As I was in biology class so many years ago for asking for "my rubber" back.)
It's a pity when words get effectively displaced from use (as, for example, it's probably nigh impossible to use "gay" in the sense of "merry"; I imagine that for nearly all English speakers, the "homosexual" meaning is the prominent one), but I imagine the pragmatical approach will be to use (globally) less offensive/risqué words even if they're (locally) not the most appropriate word.
