Bass bin is slang for the huge bass speakers found at concerts. They usually contain a small number (like 2) of very large drivers (12" or more) and are placed directly on the ground. Bass bins are designed to produce prodigious amounts of low frequency sound

The main thing about them is that they are big, really big, if it doesn't have at least one side that is over 3 feet long it is not a bass bin. QED, your subwoofer is not a bass bin.

For some reason at music festivals, small children have a tendency to climb up on top of bass bins and either dance or watch whoever is playing at the time from the best seats in the house.