This is “new-ironic“, here conveying ‘unfortunate, inappropriate’ — a usage that has been widely savaged by usage critics.
For the older usage (from Wikipedia):
Irony (from the Ancient Greek εἰρωνεία eirōneía, meaning dissimulation or feigned ignorance) is a rhetorical device, literary technique, or situation in which there is a sharp incongruity or discordance that goes beyond the simple and evident intention of words or actions.
But the word has come to take on a range of meanings having to do with surprise or misfit, including ‘unfortunate, disappointing’ and ‘coincidental’. A relatively mild criticism of this development in the New York Times of 6/30/08 (Bob Harris, “Isn’t It Ironic? Probably Not”):
Irony requires an opposing meaning between what’s said and what’s intended. Sounds simple, but it’s not. A paradox, something that seems contradictory but may be true, is not an irony. The Times stylebook, which, believe me, can be harsh, offers useful advice:
The loose “use of irony and ironically, to mean an incongruous turn of events, is trite. Not every coincidence, curiosity, oddity and paradox is an irony, even loosely. And where irony does exist, sophisticated writing counts on the reader to recognize it.”
A three-step description of the sense development, from the Grammarist site:
The misuse of ironic is a common pet peeve among careful users of English. Some of the complaints are overblown, but ironic has undoubtedly been polluted by slipshod use.
The one definition of ironic on which everyone can agree is using words to express the opposite of their literal meaning. Irony is similar to sarcasm, but the goal of sarcasm is to mock, while irony is usually used to make subtler points.
… A less accepted but longstanding definition of ironic is markedly different from what was expected. This is where ironic starts to rankle some people. But while this sense of ironic is more questionable than the original, it’s so widespread that we have to accept it. For example, it appears in these major publications with high editorial standards: [quotes from Guardian, New York Times, Globe and Mail]
While we reluctantly accept ironic as a synonym of paradoxical, incongruous, or contradictory, the word probably shouldn’t be used as a synonym of funny, interesting, improbable, [in]appropriate, or coincidental. [quotes from Fox News, Chicago Tribune, Washington Times]
What we see here is successive stages of bleaching in the word’s meaning, starting with an extension of the word to describe linguistic expressions to use for situations (like Jeremy’s dad’s costume).
[Grammarist “is cooperatively written and edited by a group of [anonymous] U.S.-based writers.” ]