monkey
mon·key
I
 /ˈmʌŋki/  noun  ,  pl   -keys [  count  ]
  1 : a type of animal that is closely related to apes and humans and that has a long tail and usually lives in trees — see also rhesus monkey
  2 chiefly Brit : a person (especially a child) who causes trouble in a playful way
   He's quite a cheeky little monkey, isn't he?
  a monkey on your back
   : a problem that you cannot easily get rid of or solve : a problem or situation that makes you unhappy and that lasts for a long time
    His drug addiction has been a monkey on his back for years.
    He finally got the monkey off his back and kicked his drug addiction.
    After many years of disappointment, she finally got the monkey off her back by winning the championship.
  make a monkey out of
    informal   : to cause (someone) to look very foolish : to make a fool out of (someone)
    I'm not going to let that salesman make a monkey out of me!
  more fun than a barrel (full) of monkeys — see barrel, 1
  not give a monkey's
    Brit    informal   : to not care at all about something.
    I don't give a monkey's about their problems!
 — see also grease monkey
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II
  verb  , -keys, -keyed, -key·ing
  monkey around ( or Brit   monkey about) [  phrasal verb  ]
     informal  
   1 : to do things that are not useful or serious : to waste time
    We just monkeyed around [=fooled around, messed around] all afternoon.
    a young scientist monkeying around in the lab
   2 monkey around/about with (something) informal
   2 a : to use or do (something) in a way that is not very serious
    He enjoys monkeying around with [=fooling around with] his car's engine.
   2 b : to handle or play with (something) in a careless or foolish way
    You shouldn't be monkeying around with dangerous chemicals.
  monkey with [  phrasal verb  ]
   monkey with (something) informal : to handle or play with (something) in a careless way : to monkey around with (something)
    I told you not to monkey with [=fool with] the lawn mower.