GG EZ means "good game, easy," said sarcastically after winning to mock the losing team. Considered rude in gaming etiquette. Some games auto-censor it. Not concerning unless your teen frequently antagonises other players. 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. Most slang of this kind moves through TikTok and group chats, so seeing it in your child's vocabulary just means they are plugged into normal teen internet culture.