The classic test of an American is, as any Englishman knows, that they don't understand the difference between sarcasm and irony.  This is why we get songs like "Ironic" (OK I know Alanis is Canadian) where her best shot was:

A traffic jam when you're already late
A no-smoking sign on your cigarette break
It's like ten thousand spoons when all you need is a knife

You see perhaps needing a knife would be ironic if, say, you happened to be the world's largest knife manufacturer but the ten thousand spoons are just unhelpful or perhaps even annoying.

Nor are they sarcastic because I really love Alanis Morisette (now that is sarcastic).

Anyway where does this deep rooted American issue originate from?  Even Microsoft Word isn't helping..  Check out synonyms for "Ironic" and yep there it is.. sarcastic..
Perhaps we need a new locale :-)