Definition of cut up in US English:

cut up

phrasal verb

  • 1North American Behave in a mischievous or unruly manner.

    ‘kids cutting up in a classroom’
    • ‘‘She was kind of getting a little antsy in there, there was a couple of horses cutting up,’ Bourque said.’
    fool about, fool around, play the fool, act foolishly, act the clown, act the fool, act the goat, play about, play around, monkey about, monkey around, play tricks, indulge in horseplay, engage in high jinks
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  • 2(of a horse race) have a particular selection of runners.

    ‘the race has cut up badly with no other opposition from England’