American English makes more use of word pictures than the King's English (UK), expressed in phrases like "a month of Sundays", "I'll be a monkey's uncle...", etc. To most people outside the US, these are unintelligible phrases that defy translation. Of course, the US is not exclusive in this type of usage, but we seem to create new colloquialisms "at the drop of a hat" (another such phrase), and sometimes these get popular use worldwide.
Americans don't generally adopt phrases from overseas very easily, but are not at all shy about looking foolish when they butcher their own native tongue. And in many parts of the USA, even a native speaker is hard pressed to understand the pronunciation of different cultural sub-groups, as in the deep South, or urban street cultures.
Homonyms (words that sound the same, but are spelled differently, with different meanings) are sometimes also difficult for native speakers, especially those who are doing live translation into sign language, subtitles, or another spoken tongue. Examples: here/hear; soul/sole; deer/dear; wine/whine. Perhaps the hardest for non-native speakers are the multi-definition words, which are numerous. Example: can(able/metal container/fire from job[slang]//butt [slang]/toilet[slang]). When a word can be used as a noun or a verb, this can be confusing!
The thing I despise the most is that people here have a tendency to turn a noun or pronoun into a verb, becasue they are too lazy to make a full description of something. So now, to go on a rampage is sometimes known as "going postal"; a macabre reference to a string of murders by postal workers who snapped mentally and shot their co-workers!
So I agree with Os on this, my "hat's off" to those of you who have adapted/are learning English in its many forms!
