Irony is one of my biggest pet peeves. It didn't start with Alanis Morisette, and her Isn't It Ironic song that had absolutely zero irony... but she just made it worse.
One of the first references to irony being ignorantly misused was F. Scott Fitzgerald. I saw this video with an editor at Merriam-Webster where she attempts to explain how ignorance isn't wrong.
I disagree with this because I don't think that ignorance means you're correct. Basically, just because some people don't understand what irony is, doesn't change the definition.
It's not just me.
The good people over at Is It Ironic? have waged war on people who refuse to recognize the correct definition of the word.
So, what is irony anyway? Irony is saying the exact opposite of the truth. Irony is sarcasm.
Irony is not coincidence. Irony isn't happenstance. Irony isn't just because you like the word and want to vocabularize your letter, paper, book, or conversation.