BUTTINSKY
buttinsky
(noun) a meddler who tends to butt in
Source: WordNet® 3.1
Etymology
Noun
buttinsky (plural buttinskys or buttinskies)
(informal, derisive, North American) One who is prone to butt in, interrupt, or get involved where they are not welcome.
Synonyms: busybody, backseat driver, kibitzer, meddler
(telecommunications) (usually buttinski) A robust portable one-piece telephone instrument with clips, used by technicians and lines staff for testing telephone circuits or making a temporary connection to a telephone line.
Source: Wiktionary