Here's a breakdown:
* Chuffed: This is a British slang term meaning pleased or delighted.
* As monkeys: This part is used to emphasize the intensity of the happiness, comparing it to the exuberance of monkeys.
So, someone who is "chuffed as monkeys" is incredibly joyful, possibly due to something good happening to them or someone they care about.
Example:
"I was absolutely chuffed as monkeys when I got the job offer!"