What's The Best Civilian-to-Military Conversion?

Just like how street cars can be turned into full on racers, when your country needs them, civilian vehicles can also act as war machines. But which is best?

Despite originating from Italy, the Vespa 150 TAP was built by licensed assembler Ateliers de Construction de Motocycles et Automobiles in France starting in 1956 followed by a minor update in '59.

The 'Bazooka Vespa' had an American M20 75 mm anti-armor cannon that was light but could also penetrate 3.9 inches of armor with a high-explosive anti-tank warhead.

Built into the Vespa's frame since there was no need for a mechanical recoil system, the scooters could be parachute-dropped in pairs accompanied by a two-man team. The French built about 500 of these powered by 146 cc single-cylinder two-stroke engines.

While it would come handy in today's traffic for sure, what other crazy civilian-to-military conversions can you show us from humanity's last war-filled century?