What dialect is Chen supposed to be speaking here? "Uchi" makes me think Kansai-ben, but "nan yo" (and "n yo" in the title) and "muzui" from the next comic seems like... one of the Kantou dialects (or Tokyo-ben itself), maybe? I dunno.
Late reply is late, but according to this site, it's not any sort of dialect, but rather a slang abbreviation that started up in the late '70s and gained widespread popularity in the mid-'80s.
