Meaning of ACT UP

WordNet Dictionary
	Definition:		[v]  make itself felt; as of recurring pains; "My arthritis is acting up again" [v]  misbehave badly; act in a silly or improper way; "The children acted up when they were not bored"
	Synonyms:		carry on
	See Also:		ache, hurt, misbehave, misconduct, misdemean, smart