An unstoppable asshole, (combination of the words Fucker and Juggernaut)
That guy at the bar was a real fuckernaut!
by ReconfigureYou March 22, 2010
2 more definitions
Someone who massively posts useless crap while trying to flame and starts complaining when is about to get pwned. Combination of Fuck and Astronaut.
Don't fucking cry about it here on the internet you fuckernaut.
by gracie-hunter September 02, 2007
Super dumb fuck... space heads
Oh my god that person is so fucking dumb his head must be in the clouds.
by Lilith Rain March 10, 2004