This insane thing is the Vespa 150 TAP, a French creation to give Paratroopers tank-level firepower, while making it as portable as possible. The cannon was intended to be removed from the scooter to use a separate tripod to properly aim it from a stable ground position- but the French seemed to figure if they'd come this far, why not go the rest of the way- the frame was reinforced so the cannon can be fired while mounted in the scooter- better still, even while it's being driven. Roughly 500 of these things were made between 1956 and 1959, with some allegedly seeing limited service in Indochina (now Vietnam). They exist today in museums, private collections, and 'Mad-Max' style fantasies around the world.
The cannon is a 75mm recoilless rifle, mostly American surplus units from after World War Two, but with a few later models being outfitted with newer "more accurate" cannons from Bofors.
