I’ll admit to having a softspot for sidecars. They are definitively eccentric.
Today’s invention is a way to store one’s three-wheel steed safely in an urban environment.

A tough, toolshed-like box fits over the motorcycle, when parked against a wall. The box is secured to the wall and when released, it rotates to reveal a sidecar seat with minimally exposed third wheel.
This is placed, for stability, beneath an arch between the occupant’s legs and driven via a chain from the bike’s back wheel.
Allowing limited, sprung, rotation between shed base and bike when in transit might actually allow a reasonably smooth ride. A small pulley arrangement might help the less brawny open and close the system.