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Verb: act up
  1. Misbehave badly; act in a silly or improper way
    "The children acted up when they were not bored";
    - carry on
  2. Make itself felt as a recurring pain
    "My arthritis is acting up again"

Derived forms: acting up, acts up, acted up

See also: act

Type of: ache, hurt, misbehave, misconduct, misdemean, smart

Encyclopedia: Act up