The bunker Christmas tree in Grand Theft Auto Online plays music. I can recognize Deck the Halls and Jingle Bells, but I don't recognize the third one. It's instrumental music only, which you can hear at 27 seconds in this YouTube Video:
4This question is being discussed on Meta– arghtypeDec 21, 2019 at 2:36
It is The Boar’s Head Carol, a 15th century English Christmas carol.
Wikipedia has samples here: