The Brief: BTW stands for "by the way."

DEEP DIVE
BTW (also pronounced “B-T-Dubbs”) is short for “by the way.” It is primarily used as a transitional phrase to introduce a new topic of conversation. BTW can also be used to interject a humorous non sequitur or to nonchalantly call attention to something important or significant, usually in an ironic way.
Thanks so much for all the Happy Birthday wishes. (And BTW I'm 83, not 84. I'll get there eventually, but I'm not rushing.) π
— Alan Alda (@alanalda) January 29, 2019
Thank you to the girl who gave me these crystals! I really needed them. I feel like Iβve had no spiritual protection out here, so this is much appreciated x (the bag is my pen holder btw) pic.twitter.com/SF2FQ0izLQ
— Emerson Barrett (@EmersonBarrett) January 29, 2019
black panther got 7 oscar nominations btw. pic.twitter.com/oz37AjU9CV
— π€π’π₯π₯π¦π¨π§π ππ« (@ki11monger) January 29, 2019