tubular, adj. — Green’s Dictionary of Slang

tubular adj.

[? surfer jargon tube, the inside curve of a good wave]

(US teen) the ultimate in perfection.

1982		Frank Zappa ‘Valley Girl’ 🎵 It’s so AWESOME / It’s like TUBULAR, y’know.
1998		D. Hecht Skull Session 144: Oh, my God. Dudical went out with tubular, God you might as well say gnarly!
2002		(con. 1980s) i80s.com 🌐 tubular Something that is cool. Something overwhelming. ‘Tubular, totally tubular.’.