Place it as the solo reaction beat immediately after the reveal line, with nothing else competing in that moment. Follow it with a stunned pause, then pair it with the oh my god wow button for a second layer of shock, or a faaaa meme hit when the surprise turns to disbelief.
Über diesen Sound
This clip is a short female voice speaking the Portuguese phrase "Tô passada!" in an exaggerated, stunned exclamation that lasts just under three seconds. It lands as funny and dramatically surprised, the vocal equivalent of a jaw dropping after hearing something outrageous or unexpected, with that theatrical disbelief turned all the way up.