bababardwan - Chinese/English homophone confusion

As English is spoken so widely in the major centres of China there may be times at first contact point between a 老外 and a 中国人 where if only a word [or two ] were spoken it may be unclear which language was being used and where there is meaning in both but different.

ok,well I'm imagining a scenario.Perhaps it is two American guys ,one an ABC and they're off on a holiday in China.They decide to buy some presents for their girlfriends back home.They're in a bit of a hurry,no time for bargaining or chit chat and the prices are very low anyhow and clearly marked and there's a line up.So the ABC guy just hands over the dough for the gift and as the vendor hands back the change he says : "给“。Now the ABC guy is standing there "What'd he call me"?

Any other examples of important Chinese/English homophones not to mix up?