English.

A U.S. Navy Admiral was attending a naval conference that included admirals from the US, British, Canadian, Australian, and French Navies.  At a cocktail reception, he found himself standing with a group of half dozen or so officers that included personnel from most of the  countries. Everyone was chatting away in English as they sipped their drinks, but a French admiral suddenly complained that, whereas Europeans learn many languages, Americans learn only English.

He then asked: "Why is it that we always have to speak English in these conferences, rather than speaking French?"

Without hesitating, the American Admiral replied: "Maybe it's because the Brits, Canadians, Aussies, and Americans arranged it so you wouldn't have to speak German."

It got so quiet, you could have heard a pin drop.

(It is rumored that this is a true story. -tmc)