At my old job I had a phone that had IR remote capability. I'd turn off or mute the blaring TVs in our break rooms. Good times.
There used to be a commercially-made tv-b-gone device. Not sure if it's made anymore, but there's a DIY kit that appears to do the same thing: https://www.adafruit.com/product/73 I used to carry one with me everywhere (it was small enough to fit on a keychain). One night at a sports bar, I showed it to a friend. Before I could stop him, he pushed the button and every TV in the place went black, right in the middle of…
Not sure about that one either but its functionality has been cloned for the Flipper Zero [1]