In the late 1980's the definition was taken to greater heights by a subculture of NYC and SF club kids. It was used to describe how one felt while on the drug ecstacy, and especially while "candyflipping" - a combination of LSD and pure pharmaceutical ecstacy. To describe a feeling of a state of eternal bliss!
Last night was amazing. The music, the people, and the overall positive energy made me feel simply fantabulous!
(stating one felt fantabulous was code for saying they were on "e")