The phrase go back to lobby comes from online multiplayer games, where the lobby is the menu players return to between matches. Shouting it at someone became shorthand for saying their game is over, they played badly, or the team should quit and restart. Short clips of the line spread on soundboards and in edited gaming videos because the wording is instantly understood by shooter and battle royale players. It is still used as a quick dismissive reaction that needs no setup or explanation.