shoo-fly (interj.) Look up shoo-fly at Dictionary.com
admonition to a pest, by 1867 (in baseball slang), from shoo (v.) + fly (n.). Popularized by a Dan Bryant minstrel song c.1870, which launched it as a catch-phrase that, according to H.L. Mencken, "afflicted the American people for at least two years." Shoo-fly pie is attested from 1935.