| 1. | frivolous or mischievous behavior. |
| 2. | improper or underhanded conduct; trickery. |

| monkey business n. Slang Silly, mischievous, or deceitful acts or behavior. |
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monkey business
and funny business
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monkey business
Silly, mischievous, or deceitful conduct, as in The teacher told the children to cut out the monkey business and get to work, or I don't trust that lawyer
there's some monkey business going on. This expression transfers the tricks of monkeys to human behavior. [Late 1800s]