The sound comes from Team Fortress 2, the Valve shooter released in 2007, where the Heavy can eat a Sandvich to restore health. The om nom nom lines were added with the Sandvich as his exaggerated eating vocalisation, performed by voice actor Gary Schwartz. Clips of the moment spread through YouTube poops, Garry's Mod videos, and gaming edits in the late 2000s and early 2010s, becoming shorthand for loud, happy eating. It remains popular because the delivery is recognisable even without the game footage.