UP-on is like HAP-en (as in 'aye HAP-en'- 'yes that right' or 'yes thats how it happened') we like some consonants to stand out, P being the main one in the phrase 'bin dow t'pit' the P is still distinct even though 'dow t'pit' is said as one word with minimal syllables (only first T is distinct).

Makes sense to us as were born here, keeps outsiders from knowing our business :p