Americans sound stupid using British colloquialisms

Really stupid.

So don't come here thinking you can say “cheers”, “quid”, “crikey”, or “mate”. You might get away with “oi” since it's close enough to “hey” that people might not be sure what you said. We've struck a diplomatic accord with our friends that if we don't say “quid” they won't say “buck”. One exception is “no worries” since that seems to have been appropriated from the Aussies anyway. But in general, resist the temptation or risk being considered a wanker.