To have an addicction, especially a drug addiction.
Man, he's got a monkey on him back! He's so wasted!
To have some very burdensome nuisance you have to put up with--in a sense wider than just a drug or other addiction.
"That huge credit card payment is a real monkey on his back." "Trying to sell that white elephant must be a monkey on your back."
To have a deep, uncontrollable desire to something such as Gamble, Smoke, or Drink.
Man he has that Drinking monkey on his back, it is 9:30 in the morrning and he's already drunk.
Addiction, mostly heroin/morphine addiction.
Hey dad, you been smacking da H again, quit it bitch, you have a monkey on your back
But the morphine eased the pain,
And the grass grew round his brain,
And gave him all the confidence he lacked,
With a Purple Heart and a monkey on his back.
There's a hole in daddy's arm where all the money goes,
-John Prine - 'Sam Stone' a song about a vietnam vet returning to the US with a monkey on his back.
Severe relentless back pain one gets during opiate withdrawal.
hardest part of detox will be the monkey on your back