Garry's Mod
From YTMND
Garry's Mod is a free Half-Life 2 mod that is used to create many HL2 YTMNDs. The most notable example is probably G-Man is Having a Wonderful Time, and the many spin offs this created. Garry's Mod is commonly used to create gifs with an actual storyline to them, as the action is changed each frame to make the HL2 player models do anything the creator desires. Garry's Mod may also be used to "remake" other fads, like Butt Racing, Zaza, etc..
