Refers to your wearing a personal music-device that uses a headset of some sort, and then "blaming it on that" whenever someone complains that you appear to be ignoring him, when of course in reality you actually heard what he said just fine because **the headphones weren't even playing at the time**, but you were merely practicing "selective deafness" because you didn't happen to like what he had to say, and so you did not wish to respond to and/or be affected by whatever he was telling you.
The headphones excuse can also be "used in reverse" in instances where you are being compelled to be present during a speech, lecture, tirade, etc., and you cannot bear to listen to said boring/controversial/voluminous b**ls**t for even a few seconds... what you do, therefore, is clip on your headphone-based music-device that's hidden inside an outer plastic cabinet that you have boldly labelled, "personal amplified listening device", so that the speaker and anyone else present will think that you are just wanting to ensure that you'll be clearly hearing every single word that the self-important gabber is saying, when in reality you are using the headphones to DROWN HIM OUT so that you won't either need a straitjacket or commit mass-homicide halfway through said extended monologue. It's a vital accessory if you're being "drugged as a child" because your parents "drug you to church".