Douglas Harper's Etymology Dictionary
monkey-shines
also monkeyshines, "monkeyish behavior, tricks, antics," 1832 (in the "Jim Crow" song), from monkey (n.) + shine (n.) "a caper, trick" (1835), from an American English slang sense perhaps related to the expression cut a shine "make a fine impression" (1819); see slang senses under shine (n.). For sense of the whole word, compare Old French singerie "disreputable behavior," from singe "monkey, ape."
Wiktionary
monkey-shines
n. (monkey-shine English)