This clip comes from the second version of Stickman Battle Round 3 Blue vs Yellow, a Flipnote Studios animation built around a fast stick figure fight. The reaction voice tracks the back-and-forth action, which is why it travelled beyond the original animation into reaction edits, prank clips and meme compilations. Creators keep returning to it because the repeated oh dang phrasing is instantly readable as shock, works without any context, and fits neatly over short fight, fail and surprise moments.