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.

You think you know English? You don't know English.

Compared to the British, Americans are newbie English users. In British hands, the English language is a tool of infinite subtlety. For example, when a Brit tells you that they “agree with you to a point”, this doesn't mean that, with the exception of a few aspects, agreement has been reached; it means they don't agree with you at all. The magazine The Economist once reported that English-speaking Dutch diplomats had to employ British translators in order to understand what their British counterparts were really saying. This adds a whole new dimension to arguments at the pub.