Use it right after a wild claim in a chat screenshot edit, then follow it with the Ceeday huh sound and cut straight to the reply that tries to explain it.
このサウンドについて
This is a short Portuguese voice clip of a speaker saying “Como assim não entendi”, asking how something can be so and admitting they did not follow it. The delivery lands as baffled and lightly comic, turning a missed point into a shared laugh rather than a serious complaint. It works best as a quick, good-natured reaction to a confusing claim.