Very similar thing happened to us. Stopped at a set of lights at Adelaides busiest intersection. A cyclist stopped and lent on the rear of the car. We rolled back and forward and he still lent there. I knew the light sequence so just before they went green we dropped the cluch and took off. The cyclist almost fell off in front of all the traffic as he tried to get control of the bike. The sight of him swerving all over the road trying not to fall off was priceless.
That was about 15 years ago and we still have a good laugh at it.