Place it right after Balou's name is mentioned, at the start of the reaction beat, then follow it with Oh My God Wow for a bigger response, or with Ceeday Huh for a second reaction in the same sequence. Keep it as the first response in the sequence so the later sounds build on it.
Über diesen Sound
This is a very short spoken reaction, lasting under a second, in which a voice says 'Oh Balou'. The line feels playful and caught off guard, like a friendly call-out when a familiar name suddenly pops up in conversation. It lands as a light, teasing response rather than a serious remark, making it easy to recognise and fun to replay in the right moment.