Nathan Fillion uses the phrase Full On. Its short form is: FO. It is often used in conjunction with phrases such as: Double Rainbow, Double Rainbow, All The Way, and Double Rainbow, All The Way Across The Sky.

It means that which is:

•fully ecstatically wondrous

•beyond joyfully amazing

•intensely orgasmically blissful
Here are some usage examples for Full On. (For more examples, see the Twitter page belonging to NathanFillion:)

Nathan Fillion, on his Twitter page, kindly acknowledged my entry work defining his recommendation of the new "in" phrase: "Double Rainbow" on Urban Dictionary! He said it is "Full on." Thank you, Nathan. You are so Full On Double Rainbow, All The Way Across The Sky! (FO DR ATW ATS!) (See also: FODRATWATS)

The TV shows Castle and Firefly are so intense, they are Full On Double Rainbow!.

Serenity, the feature film starring Nathan Fillion, is so vivid, it's Full On Double Rainbow!

Nathan Fillion is so awesomely spectacular, sexyhotmessgorgeous, and brilliantly talented, his fame is sweeping across the nation, and over all the world! Nathan Fillion is Full On Double Rainbow, All The Way Across The Sky!
by Kcat10 August 01, 2010
Top Definition
Adjective. A particularly intense or extreme experience, whether good or bad.
"The party got a bit full-on when those randoms turned up with all that crystal meth."

"He told me he loved me...I've only known him three weeks so it was all a bit full-on."
by Muffin Freak March 02, 2006
<adverb> British Slang;

1) Synonymous with 'absolute', 'positive', 'total' etc...
"Jonathan is an absolute, full-on knob-head!"
by Stuart Fletcher November 15, 2004
One of the premier trolls to ever step into the black metal internet circles, and specifically the FMP ring. Known to be absolutely crazy.
"Fullon.... come..... to.. Alberta........"
by Procyon November 29, 2006
Adj, holding nothing back. intense, relentless.
no way mate, that was so full on its doing my head in.
by herbie August 25, 2004
An adjective expressing anything to the extreme.

Full on hungry. Full on pissed.
by Jess Face September 02, 2005
The absolute whole amount of something, maximum quantity or intensity, such as turning a tap on full, it is all go, all happening and 'full on'.
Rents: " How is University?"
You: " It is full on, I have 2 assignments due tomorrow and a 4 hour lab this evening, exams next week, a cold coming on, no money, no food in the house and everything is just FULL ON!"
(oh yes and I forgot to mention my hot date later tonight~ I got the cold, and the cold sore off them as well;)
by Intensity May 22, 2006
having a strong or wild personality, audacious
Tawny is making out with some random dude and shouting at the boat captain to be a man and speed up. That girl is so full on.
by Carlo R. April 03, 2008
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