Place it right after the reveal shot, once the total is on screen, then follow it with the Windows XP Error Sound before cutting away. For a bigger finish, save the WTF Boom Sound Effect for the final frame after the reaction has settled.
このサウンドについて
This is a short Brazilian Portuguese voice clip, lasting about two and a half seconds, in which someone says “Porra, tudo isso?” — roughly “Damn, all that?” — with a blunt, rising delivery. It feels instantly surprised and disbelieving, as if the number, price or result is far bigger than expected, and it lands best as a quick human reaction to an absurd reveal.