monkey business UK /ˈmʌŋkɪ ˌbɪznɪs/US /ˈmʌŋki ˌbɪznɪs/ noun2 •(informal) Activity that is mischievous, stupid, or time-wasting.Stop all this monkey business and do your homework! •(informal) Activity that is morally questionable or even mildly illegal.She wondered what sort of monkey business her neighbour was up to, sneaking out of his house at 1:00 am.
