ham it up
ham it up {v. phr.}, {slang}
To do more than look natural in acting a part; pretend too much; exaggerate.
When Tom told the teacher he was too sick to do homework, he really hammed it up.
The old-fashioned movies are funny to us because the players hammed it up.
Compare: LAY IT ON.
Categories:
Source: A Dictionary of American Idioms