LTG refers to LowTierGod, a fighting game streamer known for blunt, rant style reactions that are frequently clipped and reused online. Short lines from his streams circulate as standalone reaction sounds because the delivery is recognizable even without video. You thirsty spread in that format, used as slang for calling someone desperate for attention, approval or a response. The clip keeps being reused in gaming and streaming edits where a quick, dismissive put down fits better than a longer rant or explanation.