Place it at the end of a clutch or taunt sequence, after the payoff lands, then follow it with a Vine Boom for impact. For a failed brag, put a SpongeBob Fail before it so the grin reads as the comeback.
About this sound
A just-over-a-second Team Fortress 2 reaction clip from DasBoSchitt, built around a smug, shit-eating grin with no dialogue, just a sharp, cocky musical beat. It feels cheeky and shameless, like a knowing smirk after getting away with something, and it instantly frames a lucky play, taunt or narrow escape as deliberate confidence.