used for internet memes. An obnoxious way to say “Oh, My God” with strong emphasis on the R sounds. Typically followed by other words with emphasis on the R sounds.
ERMAHGERD, ERNSTAGERM (Oh, my god, Instagram)
ERMAHGERD, MER FERCE HERTS (Oh, my god, my face hurts)
via Urban Word of the Day http://www.urbandictionary.com/define.php?term=ermahgerd&defid=6659968