What is You're Gonna Have a Bad Time?

A warning line said by Sans the skeleton in Toby Fox's RPG Undertale, used by fans as a Genocide Route catchphrase.

Where did You're Gonna Have a Bad Time come from?

The line appears in Undertale's 2015 Genocide Route when Sans judges the player. South Park used the same wording earlier, in the March 13, 2002 episode "Asspen".

What does You're Gonna Have a Bad Time mean?

It signals that whoever hears it is about to get wrecked, framed in Sans's calm deadpan.

How do you use You're Gonna Have a Bad Time?

Fans caption fan art or reaction edits with the quote, often alongside the Sans sprite with its glowing eye socket and Megalovania playing in the background.

Is You're Gonna Have a Bad Time still popular?

The line stayed active in the Undertale fandom well after the game's 2015 release, with fan art and Megalovania remixes keeping it in circulation.

You're Gonna Have a Bad Time

2015catchphraseclassic

Published October 24, 2026

"You're Gonna Have a Bad Time" is a warning line from Sans the skeleton in Toby Fox's 2015 RPG Undertale, said when a player attempts the Genocide Route after killing enough monsters to trigger his judgment. Sans delivers it to foreshadow the brutal fight waiting at the game's finale, and the line took off alongside his battle track Megalovania. By late 2015, Undertale fans on Tumblr and YouTube were captioning fan art with the quote whenever a situation looked doomed.

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Overview

Fans deploy the quote whenever a character is about to get destroyed, often alongside a Sans sprite with his left eye socket glowing cyan and yellow3. Variations substitute Sans for other threatening figures, overlay the Megalovania intro on unrelated clips, or redraw Sans's judgment speech with MS Paint art1. Captioned fan art leans on the eye glow, the dark hallway behind Sans, and the exact game dialog box1.

Urban Dictionary definitions tied the line to any clear-cut threat with a Sans voice behind it5. Sans's deadpan delivery drives the humor, so the catchphrase works best when the setup is innocent and the warning arrives flat.

Gallery

Origin & Background

Platform

Undertale (video game) / Tumblr (viral spread)

Date

2015

Undertale developer Toby Fox wrote the line as part of Sans's judgment speech, which triggers when a player reaches Snowdin after killing every random encounter in the Ruins3. Undertale released in September 2015, and Sans delivers the warning twice: once before the Papyrus boss fight and again during the Judgment Hall scene preceding Sans's own showdown3. The exact wording itself borrows from the South Park episode "Asspen," which aired March 13, 2002, where a ski instructor repeats "you're gonna have a bad time" throughout a lesson2.

Fox composed Sans's battle theme, Megalovania, as a reworked version of a track he wrote for Radiation's Earthbound ROM hack Halloween Hack, later remixing it again for the Homestuck soundtrack3. The meme creator is unconfirmed; Toby Fox wrote the dialog, but the online spread came from Undertale fans in late 2015.

How It Spread

Undertale fans adopted the line as the signature taunt of the Genocide Route, posting it under fan art of the Sans fight and over reaction edits of unrelated media3. Megalovania saw heavy fan remixing, with amateur covers and poorly made recreations compounding the quote's reach4.

By early 2016, YouTube hosted countless Sans fight reenactments, hand-animated boss parodies, and "you're gonna have a bad time" sound alerts4. Urban Dictionary users logged the quote as a signal that someone was about to be wrecked5. Years after Undertale's release, the line still appeared across Undertale subreddits and Tumblr tags whenever fans wanted to telegraph a doomed outcome3.

Timeline

2002-03-13

South Park episode "Asspen" airs, featuring a ski instructor who repeats the "you're gonna have a bad time" line.

2015-09

Toby Fox releases Undertale, with Sans delivering the warning on the Genocide Route.

2015-10

Undertale fans on Tumblr and YouTube start captioning fan art and recreations with the quote.

2016

Megalovania remixes and Sans boss parodies multiply on YouTube, carrying the line further.

How to Use This Meme

A common convention is to post the Sans sprite with glowing eye and dialog box over a scene where someone is about to get wrecked, often with Megalovania playing. Users typically keep Sans's flat tone intact, so the line reads as a casual sentence spoken right before disaster hits.