second banana
1. A performer who acts as a support to a lead comedian (the so-called "top banana"), as during a burlesque or vaudeville routine. I generally don't mind playing second banana when I'm with such a legendary comedian, but it would be nice to be the one getting all the laughs once in a while.
2. By extension, someone who occupies a secondary, lesser, or subservient role or position. I've been second banana in this company for too long now. I'm going to start up my own business, and then I'll be the one in charge!