In a sea of disc braked mtbs and hybrids, there was this excellent reverse steer folder. I am pretty sure that it belonged to a street performer.
If you were, as I was, expecting a sea of eastern block knockoff Raleigh D bikes, you and I were both mistaken.
Update from the Pfister in the comments:
I rode that bike (or maybe a clone of it) in London about 10 years ago. It belonged to a street performer who would chalk two lines about 20 feet apart and offer rides for 1 pound. If you could ride the bike from one line to the other without dabbing he would give you 20 pounds. He was able to ride the bike around to demonstrate that it was possible.
I gave it a try, and decided to cross my arms to short-circuit any learned body english. But I still only made it about 10 feet.
There you go, thanks Marc!