Place this clip right after the failed line in your edit, then follow it with a huh reaction for the confused response. For a bigger pile-on, add a wrong answer buzzer later when the speaker tries again and fails a second time.
Over dit geluid
A very short processed voice clip, just 0.6 seconds long, built around the complaint that the speaker's voice is breaking. The delivery is altered with a voice-changer effect, which makes the moment feel awkward and funny at once, like a call going wrong in the middle of a word before anyone can recover from it properly.