Behave troublesomely (3,2)
I believe the answer is:
act up
(Other definitions for act up that I've seen before include "Become unpleasant" , "Behave badly (colloq.)" , "go wrong" , "malfunction" , "create fireworks display?" .)
I believe the answer is:
act up
(Other definitions for act up that I've seen before include "Become unpleasant" , "Behave badly (colloq.)" , "go wrong" , "malfunction" , "create fireworks display?" .)