someone who has no business riding a bicycle. Or even walking next to one. Watching them attempt to do so falls somewhere between a child's first try on two wheels or your 83 year old grandmother who happens to have Parkinson's disease ride a bicycle. Similar to the term "pushing mongo" often used to describe a skateboarder who pushes with the wrong foot.
Check out dude riding longo!!! He nearly got hit by that car then ran straight into the bus stop! Ha! Awesome. Idiot...