Throwback Thursday. Used on Instagram when you post an old picture of yourself on Thursday. Old pic should be from a different era of your life, not last week. Bonus points if you theme it to the time of year you are posting e.g old Halloween pic at Halloween.
by TheBearodactyl July 25, 2013
Get the #tbtmug. Originally "throwback Thursday" but now often used on other days. Can now stand for "throwback to" to indicate an old photo, thought, idea, etc. Often used in social media to reminisce, as usually social media is supposed to show the "here/now/recently."
by s2m January 1, 2014
Get the tbtmug. 
(T)hrow(b)ack (T)hursday. A social media post that references the past. Basically the same thing that the Timehop app does for you every day. Usually used in the form of a hashtag.
by kevrone March 4, 2014
Get the TBTmug. by Yasmin and Natalie February 7, 2009
Get the TBTmug. 