A derogatory term to refer to cheaply mass produced stock made in China that people do not generally use or need and shipped around the world. The stock arrives on huge super ships and the mouths to several ports have had to be widened to accept the super ships. Items then delivered by ship are then considered to be bay wideners.
G: Look at all the stuff in that shop, who would ever need any of that?
M: Oh that stuff is just bay wideners.