Sans.

sans. is the 15th track in the Undertale Soundtrack. It plays during Sans's introduction, in the rooms that contain his sentry stations, inside Grillby's, and in Napstablook's snail farm.
== Trivia ==
* The track appears to predate Undertale's development, having shown up as background music for a Homestuck-related project as early as October 2012, as "muscles.mp3", explaining its filename in Undertale.
** The original music file is reused in Deltarune Chapter 2 and its OST.
* This track was used as background music for Undertale's Kickstarter video, along with some others.
* If Papyrus is killed, Sans does not appear at any of his sentry stations. This track stops playing in Grillby's and does not play in Napstablook's snail farm.
* The OST version is slightly longer as it has a few more notes at the end from the cowbell.
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