Place this clip right after the questionable claim in your edit, then follow the reaction with a wrong answer game show cue if the proof never arrives, or a sudden suspense sting when they actually start searching for receipts.
關於此聲音
A short Portuguese voice clip, about two and a half seconds long, where a speaker first says they do not know and then firmly demands proof with eu quero prova. It feels skeptical and playfully confrontational, turning simple disbelief into a funny challenge that makes the listener want evidence before accepting anything.