A Honda 49 cc Monkey bike.
I know this will seem a bit ridiculous to all you bikers out there, but I didn't own it for very long and I still had the Norton Commando and the Bultaco Sherpa anyway. But a friend had offered it to me for free, and I thought it was fun. Besides that, I was overhauling the motor of the Commando at the time, and given that the Sherpa was not licenced for the road, I needed something to run down the road to get parts from time to time in London. Well, that was an excuse really as it was better to take the car for that. I would put it in the back of the car (which was a Minivan at the time) and used it when visiting friends out of London.
Why was this thing called a Monkey bike? I suppose because one looked just like a monkey perched on it with arms and legs sticking out. It was a hoot to ride, and I could even take it around the tiny garden back of the house I was living in in London at the time, making ramps to jump off and so on. The neighbours loved that of course. I think I gave it away in the end.