The phrase comes from 'The Boys Are Back in Town,' the 1976 hit single by Irish rock band Thin Lizzy from the album Jailbreak. The song became a staple of classic rock radio and sports arenas, and its chorus has long been used in films and trailers to mark a heroic return. Online, the respelling as 'boiz' gave it a meme twist, turning the rock anthem into a short soundboard clip for ironic, over-the-top squad entrances on social media.