"mistake," 1954, apparently a reduplication of boob "stupid person," which had acquired a secondary sense of "foolish mistake" (1934). In 1930s it was the nickname of Philadelphia gangster Max "Boo-Boo" Hoff.
Entries linking to boo-boo
boob n.
"stupid person," 1909, American English slang, perhaps a shortening of booby. For the "woman's breast" sense, see boobs. Mencken seems to have coined booboisie (1922).