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general::
Phrase(s): by guess and by gosh [and] by guess and by golly
Rur. by estimating; without careful planning. • Jane: Did you have a plan for putting up that toolshed? Tom: Nope, we just sort of did it by guess and by gosh. • Grandma always made dresses by guess and by golly, without using a pattern, and they always turned out just fine.
McGrawhill's American Idioms And Phrasal Verbs