I've seen discussions of placeholders in Japanese which seem to centre on how to pronounce written placeholders like OO, XX, etc. See below for reference:
- How do you pronounce "☓☓" as a placeholder?,
- Uses of [◯]{まる} symbol in Japanese typography
- What's the substitute word for missing/unimportant part of sentence?)
But what about an example of a placeholder used in natural speech (i.e. not reading text)? In English, an example might be somebody saying "Look over there at whats-his-name". In Japanese, it would seem strange (to me) to use だれだれ in such a real-time spoken example, like あそこにいるだれだれを見て。What word might replace it? Are there such equivalents to the English words like 'whats-his-name"?