I almost forgot about the tramp's bike I saw a while ago. It was literally a tramp's bike, he was pushing it along the pavement laden down with his belongings stuffed into panniers and tied onto various parts, as well as - the unusual bit - a two-wheeled shopping cart towed behind it. Unfortunately the hitch or possibly knot was hidden under his hordes of stuff so I don't know exactly how it worked or whether he ever rides it, nor whether it even was rideable.