The phrase "big ham" typically refers to someone who enjoys being the center of attention, often acting in an exaggerated or dramatic way. Full definition
Billy Crudup is a little subdued as Will, but then, that fits the character — it wouldn't really work if he were as big a ham as his father. (mutantreviewers.wordpress.com)
Growing up my family always gathered after Easter Mass, and had a big ham dinner with all the trimmings, and that always included pie for dessert. (delightfulemade.com)
As you can see, the Apple Lips are not the only ones who are big hams. (cookandbemerry.com)