Bad Time Simulator began as a fan-made recreation of the notoriously difficult Sans boss battle from Undertale, letting players practise a fight that many found almost impossible to beat. Clips from the game spread through gameplay videos, streams and short-form edits, where the phrase became shorthand for an unfair or doomed challenge. It remains popular because the reference is instantly understood by gamers, even without context, and because it fits any moment when someone is about to face overwhelming odds.