Based on your description, it sounds like an unaspirated /p/. If that’s the case, it does exist in English, just not in that position. It would be the sound of the p in “spin.” Or, for an easier way do to it, whisper a /b/
If it’s not that sound, the only other sound I could think would be half-voiced, which would be like saying a /b/ in a breathy voice.
That’s basically it, as I understand. And thanks, Ashley Pomeroy, for finding the right explanation for Poo’s name (chompoo are interesting crunchy pink fruits, and the word also is part of the color name for “pink”).
Pretty much everyone in Thailand has a nickname of some kind, and some of them can seem pretty weird: there are Thai words (“Lek”, “Nit”, “Noi”) but there are also things like “Beer”, “Bass”, and three guys we knew named “Grim”, “Phenix”, and “Fighter”(!)
Yeah, looking at the Wikipedia page for Thai phonology, it appears that it is an unvoiced, unaspirated bilabial plosive (or, like you say, an unaspirated “p” sound.) And, yes, “spin” is the word used as an example of this sound in English.