Seen this in a few movies, spelling is probably incorrect. It appears to be an irish-american slang for an idiot in usage. Mostly interested in the correct spelling/actual word(s) and origin.
The usage I noticed this in recently was in 'The Equalizer (2014)', the quote's context is reproduced on this page (search for 'flipperhead' or scroll down).
This is the scene in question (warning; NSFW language). I'd swear i've heard the term before in the same context (movie american-irish people insulting people).