Green’s Dictionary of Slang

number ten thou adj.

also number ten thousand
[for ety. see number ten adj.]

(US) extremely bad, dire, the very worst (cf. number one thousand under number n.).

[US](con. c.1970) G. Hasford Phantom Blooper 48: We said, ‘You baby-san VC.’ And she said, ‘No VC. VC number ten thousand.’.