DGTB is used to encourage someone (e.g. a close friend) to succeed in their day.

A close friend: Morning.
U: Good morning!
*talking for a while about meaningless things*
A close friend: Hey, I have to get going. My class is starting in 5.

U: Sure, do good today bitch!

Used often by the youtuber Jermbot at the end of his videos to encourage his followers.
by Writing Facts April 29, 2020
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Andrew texted me DGTB last night before he came in to hook up with me
by GossipGay September 1, 2009
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