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.
Just like a bag that is brought at any show off poor carnival folke, it is full of shit. You call someone a showbag if they lie or say something you don't agree with
Scrim: "Hey Gav, I'm better than you at table tennis"
Gav: "As if scrim, your such a showbag"
A Shenzhen Showbag is a bag full of Shenzhen Specials.
Various 'Deal a Day' web sites around the world will offer a 'Bag of Crap' or a 'Bag of Pooki' every now and then, which is basically stuff they had left in the warehouse and need to shift to make way for more Shenzhen Specials.
Typically you'll pay $30 for a Shenzhen Showbag which probably has a real value of maybe $5.
"Whadya get in ya Shenzhen Showbag?"
"Um, a USB hub, a USB vibrator and a USB "How to USB' guide-book on USB."
A bottom-dwelling fish such as Carp, or more commonly Cod that is reknown for their undesirable or unpalatable flesh and/or offal.
Fisherman 1: "I've got one!"
Fisherman 2: "What'd you catch?"
Fisherman 1: "Damn, it's just a showbag."
Fisherman 2: "That's a cod. Why do you call it a 'showbag'?"
Fisherman 1: "Cos it's full of shit."