"adopt maxxing" means adopt maxxing is the obsessive, strategic pursuit of collecting every possible adoptable pet, character, or item in a virtual world — treating the adoption mechanic as a min-maxing exercise rather than casual play. It is one of many casual words teens pick up from friends, social media, music or sport, and on its own it carries no particular warning. If you hear your teen use it, it is fair to ask what they mean by it in their friend group, since meanings drift quickly. Asking out of curiosity rather than alarm tends to keep the conversation open and useful.