This word is based on the artist Micky Yoochun of the Korean boyband DBSK, whose name 'Yoochun' ends with 'Chun' and is known for being (thinking he is) amazing/fantastic.
Girl #2: Yeah it was Chuntastic! :D
In Rocky II its said atleast 10 times to show the awsomeness of Rocky.
Its a word that mostly people with IQ over 150 like to use, because not everyone knows about it.