Place it right after the reveal of the sneaky act, at the start of the reaction beat, then follow it with the game show buzzer for a verdict and the Bruh sound for disbelief, keeping it first before any other reaction.
Über diesen Sound
This is a two-second shout of Seu Madruga yelling “ladrão”, the Portuguese word for thief, in the loud, dramatic voice of classic television dubbing. It feels instantly funny and accusing, like catching someone in the act rather than making a real warning. The line comes from El Chavo del Ocho, the comedy created by Roberto Gómez Bolaños.