Green’s Dictionary of Slang

(US) nothing, with inference that the subject is additionally worthless.

1939		Pittsburgh Courier 15 July 12: Your company ain’t worth doodIey now [HDAS].
1950		Goldin et al. DAUL 60/2: Doodley, n. (Carnival) Nothing. ‘A million-dollar cross-fire (high-pressure talk) wasted on that mark, and we wind up wifti doodley for our end (reward).’.
1974		(con. late 1940s) E. Thompson Tattoo (1977) 436: This college shit don’t mean doodley if you lose your friends.
1984		Fall Guy [ABC-TV] Take off them glasses. You can’t see doodly as it is [HDAS].