The line comes from Valve's Portal, the first-person puzzle game released in 2007, where players use a portal gun to solve test chambers overseen by GLaDOS. Her phrase became shorthand among players for finally grasping a clever, lateral solution, and it travelled beyond the game through gameplay videos, edits and memes. It remains popular because it is instantly recognisable to gamers, while also working for anyone who has just had a lightbulb moment.