A lore drop is when someone suddenly reveals a lot of backstory about themselves or about a celebrity, game, or TV show. "She lore-dropped about her ex at brunch" means she told a long, juicy backstory. Comes from gaming, where "lore" is the game's mythology. Not concerning, just teen vocabulary for sharing personal history dramatically. Often used playfully. If your kid uses it constantly, ask them where they first heard it, not to police their speech but to understand which online community they are in.