This wording is so interesting. It’s funny and fun when I hear or see it, Because there’s similar culture in Japan too. In Japanese, there’s nothing that is the same wording. I mean of course there’s the translated words but in Japanese case, it rather be action more so than speaking. Like if I say this in English, I did wait-what yesterday, I’m wait-whating now, like that.
Such as when a guy is walking and finds a cute girl as he is walking, but the timing was bad. She is behind him, he turns around a bit to look at her. This is “wait-whating”. He found in his mind, “wait, what? a cute girl? Was she cute or did I misunderstand?” like this. So the mind is the same as English. But most Japanese don’t say a word when someone was suppressed. If they would say something, it is “E?”, it’s not a word but only sound. It’s like Oh, woah. So basically Japanese don’t say “wait, what?” but we also do wait-what.
E is not the same “Eh”. it is Just a sound. when some Japanese say so, their mind would be as to say “wait, what?”. I hope this topic could help your understanding some Japanese mind and situation speaking. Thank you for wait-whating this post.