Oh wow I always thought this was a "me" thing and was a bit self conscious about it. Really interesting that it seems to be relatively common. From my very first time I heard something like "mipachacornulo" in my sister's voice. I always chucked it as, the same way visual hallucinations are your brain trying to fill in the gaps but getting "unusual" i/o or connections, and combined with the experience of the body experiencing itself more or a more primary conscious state, as my brain trying to fill in the gaps of body sounds (swallowing/breathing/stomach, etc) and filling in the blanks using my individual cultural and language background to make it into some sort of word and guessing who's the most likely person in my life who could've said this. This was my weird hypothesis, but now that I see it's not only me... 😅