But the term has a loaded, negative connotation. It's basically saying Irish people get so intoxicated, they forget to say goodbye -- which is not wholly untrue, given my experience with Boston, Ireland, and my own family. Or in some variations, it's a reference to Potato Famine refugees who left Ireland without warning. The term's common variations (the French farewell, the Dutch goodbye, etc.) are pretty much not-so-vague cultural slander, too. Any way you verbalize it, you're saying, "hey, that's a dick move!" and nothing else.
And to get this out of the way: The Irish exit is not "ghosting," as that word almost exclusively pertains to dating now. Ghosting has become a ubiquitous term for unceremoniously signing out of a relationship, a millennialized "going out for a pack of smokes and never coming back," fit for a 140-character-limited world. This is not what we are talking about. This isn't about leaving your S.O. and/or family and never speaking to them again to escape the mortal coil you brought on yourself. It's about leaving a bar/party/box social without exchanging frivolities. Way different.