The full form of TBIB is The Beast Is Back
TBIB stands for “The Beast Is Back”. In this context “beast” can refer to a person, object, or group that has returned with a vengeance. Commonly this is used in a positive manner. Referring to oneself as the titular “beast” is a boast that you are now a force to be reckoned with or have come back with a positive change. Likewise, saying that a sports team is the “beast” means that they have new players or a coach and will be doing well this season.

Origin of TBIB
TBIB originated sometime during the 20th century, likely during the 1980s. The most accepted theory is the slang originated among sports news cast who would declare players returning to the game after an absence as “the beast” and that opposing teams had something to fear with that player back. TBIB began to see common use throughout the 1980s and 1990s, still being used as a boast. While still seeing common usage during the 2000s, TBIB’s popularity skyrocketed with the advent of Twitter and the use of hashtags.