Place this last in a Spy sequence, after a revolver pew pew and a classic punch for the sapper hit, so the line closes the play before you move to the scoreboard or the next round's rollout.
About this sound
This 1.7 second clip is the Spy from Team Fortress 2 shouting 'Yippie ki yay' in his smug, triumphant voice. It feels cheeky and victorious, like a taunt after getting away with something sneaky. The line comes from the Spy class in TF2, where his cocky delivery makes even a quick celebration sound like mockery.