1. Somebody who just likes to talk and talk and talk, though their words have no real meaning or basis in reality.
2. A person who, like a showbag, is full, to the point of exploding, of shit.
Those four days your mother was in town were a nightmare. That woman is such a fucking showbag, I just wanted to drive knives into my ears.
Showbiz Pizza was a restaurant chain in the early 80s to late 90s. The pizza parlors were known for their animatronic rock band, the Rock Afire Explosion. While on the verge of bankruptcy they bought the Chuck E. Cheese’s Pizza Time Theatre and in a process known as Concept Unification they converted every Showbiz Pizza to Chuck E Cheese’s.