overacts manically

Your reaction to Be Kind Rewind depends entirely on how you feel about actor Jack Black. Playing the catalyst for both the ruination of a business and the salvation of its owners, Black does what Black does best: overacts manically, gesticulates madly, and makes veins throb (his and ours) as he tears up a scene.
-- Jack Black attack! in The Vancouver Courier, Friday February 22nd 2008

Trying for maniacally, no doubt.