A bicycle of a certain style usually made pre-1990, with thin wheels and a thin frame. They are usually found or stolen rather than bought and are often a mismatch of numerous bikes to create the optimum level of comfort and speed. Most are now found through hard-rubbish collection or at dumps and ridden by young folk.
"You should see the granny basher I picked up yesterday, it is heaps good"
"Fuck dude, you really have to stop thrashing that granny basher so hard, hard-rubbish isnt until October"