The Alien Egg Nobody Was Meant to Find
Buried in GTA V's game files from launch was a glowing alien egg that only third-party trainers could ever spawn, completely unreachable through normal play. Years later, Rockstar brought it back for real in GTA Online's Gunrunning update, hiding it behind an absurdly specific condition: finish 600 resupply missions, then start one more between 9pm and 11pm and hope the game rolls it for you.