Having sent "Happy Independence Day" messages to some special friends in the United States today, I remembered how I got the wrong end of the stick one evening while I was spending Christmas with them in 2002. [To "get the wrong end of the stick", by the way, means to misunderstand a situation.]
It happened like this: on this particular evening, my friend's son had been very naughty and she told me that her husband was pissed. "To piss" of course means "to urinate"" but to be pissed, in British slang, means to be drunk [ubriaco]. In American slang the expression means to be angry so you can see how I misjudged my friend's husband's state of mind!
We have to be very careful when we use slang in a language that is not our own, partly because of the danger of using it inappropriately and partly because slang becomes outdated very quickly and can make you sound really strange! As you will have understood from my story, even an English speaker from a different anglophone culture can make a mistake with slang.