“Chew the scenery” means to overact, or be melodramatic. In other words, “ham it up.”
Brewer’s Twentieth Century Phrase and Fable says the phrase was invented by the New York columnist and wit Dorothy Parker in one of her scathing reviews around 1930. But it’s older than that. There is a much earlier example in the Rocky Mountain News of March 1891. It has been so much used now that it’s become a cliché.
The phrase is often used disparagingly, but when the theatrical work is a comedy or deliberately melodramatic, a certain amount of chewing the scenery may be entirely appropriate. Gilbert and Sullivan comic operettas come to mind. And let’s not forget the melodrama in far too many political speeches.
And let’s not forget the drama queens in our own lives, the relatives and/or friends who can make the smallest event into a major happening.
Actors and politicians both often ham it up in a portrayal of frenzy so great that it appears they might really bite a chunk out of the set. Or the microphone. Some might think, from the speechifying, that the speaker is spirited and intense, but you have to pay attention to what is actually said, which may amount to nothing.
“Scenery,” by the way, refers to the backdrop, not the furniture or props on stage, which means that the phrase was originally used for the theater, not film. The world’s first full-length feature film, The Story of the Kelly Gang, made in Melbourne, Victoria, Australia, was not made until 1906.
I have no talent for chewing scenery. Long ago, when working in live theater, I was invited to be part of a screaming crowd scene, but failed miserably at appearing animated. I ended up back at my bookkeeping desk, screaming at the debits and credits.