The 'You Wanna Have a Bad Tom?' meme originates from a 2016 YouTube parody titled 'UnderPelo - Genocide Ending' by animator Sr Pelo. The video features an intentionally poorly drawn, hyper-aggressive version of the Undertale character Sans, referred to as 'SANESS.' Instead of the iconic line 'Do you wanna have a bad time?', the character screams 'DO YOU WANNA HAVE A BAD TOM?' accompanied by high-volume, distorted sound effects and a frantic version of 'Megalovania.' The meme became a staple of surreal internet humor, often used to represent loud, chaotic energy or to parody the intensity of the original Undertale boss fight.