pickmonkey on one's back . monkey on one's back {n. phr.}, {informal} An unsolved or nagging problem. "My math course is a real monkey on my back," Jack complained. Compare: ALBATROSS AROUND ONE'S NECK, MILLSTONE AROUND ONE'S NECK. Categories: add yours informal noun Source: A Dictionary of American Idioms Subscribe to: American IdiomsEnglish Slang Add my comment