Sans is the laid back skeleton brother of Papyrus in Undertale, the indie role playing game released in 2015 and created by Toby Fox. Characters in the game speak through short text box sounds rather than full voice acting, and Sans was given a distinctly lower, slower blip that matches his relaxed personality. As Undertale clips, comics and fan games spread on YouTube and social media, that blip became shorthand for the character himself, so fans now recognise the sound instantly even without seeing him on screen.