git gud

Deliberate misspelling of get good; see get (“to become”).

git gud

1. (Internet slang, derogatory) To improve; to develop skill or expertise.
   • 2017, Zek Valkyrie, Game Worlds Get Real: How Who We Are Online Became Who We Are Offline:

     They are also often cast as elitist scum who treat the larger gaming population with disdain, telling them to “git gud,” which is akin to a “put up or shut up” mentality; that is, “real” gamers overcome content through hard work and skill.

   • 2019, Tee Morris, Twitch For Dummies (page 278)

     […] showing off what he knows but more about helping out a streamer and a friend who is looking to “git gud” at this whole Twitch thing. He embodies all the best qualities of Twitch; […]

• Generally used in the imperative as an insulting way to call attention to somebody's lack of skill in a video game, etc.