The sound comes from the Team Fortress 2 community, where the Spy is one of the game's original classes from Valve's 2007 shooter. FemSpy is a fan made female version of that character, popular in mods, Garry's Mod videos and Source Filmmaker animations, often with custom voice lines recorded to replace the original Spy's sounds. Short pain reactions like this one spread through soundboards and editing packs because they are instantly recognisable to TF2 fans, easy to drop into any clip, and funnier than a generic scream or grunt.