IDIOMS

chew the scenery

(idiomatic, performing arts) To display excessive emotion or to act in an exaggerated manner while performing; to be melodramatic; to be flamboyant.

Example: 2006 October 11, James Poniewozik, "Fall TV Preview," Time:
  Starring as a Great White Hope police commissioner sent to clean up Washington, D.C., Nelson displays a set of pipes barely hinted at in his years on "Coach," spending the long pilot hour barking, bloviating, singing(!) and generally chewing the scenery.