naked as a jaybird

Bare, unclothed, as in I came straight out of the shower, naked as a jaybird. This simile replaced the 19th-century naked as a robin and is equally unclear, since neither bird is normally stripped of its feathers. Further, the bird it refers to is more often called simply "jay" rather than "jaybird," yet the latter is always part of the simile. [c. 1940]

The adjective has one meaning:

Meaning #1: (used informally) completely unclothed
  Synonyms: bare-assed, bare-ass, in the altogether, in the buff, in the raw, raw, peeled, stark naked