What does 'Flipperhead' mean?

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).

It's Bostonian. The concept comes from the thalidomide babies born with "flippers" for limbs in the late 50s. The idea is that instead of arms or legs it was your head and your brain that were stunted and came out as a flipper. It's a way to say you're a monumental, irretrievable, freakin' idiot.