double-O

[duhb-uh l-oh] /ˌdʌb əlˈoʊ/
noun, plural double-Os. Older Slang.
1.
careful scrutiny or close inspection.
Origin
1915-20; after the two o's in once-over
Slang definitions & phrases for double-O

double-o

verb

To examine carefully; scrutinize: I stop a second to double-o the frame

[1917+; fr the abbreviation of once-over]