People invent things and among them why not a Bazooka, some are more versatile than others, some more or less powerful. But everyone does it with a playful intention.

A good examples:

This is the "Made in Spain" BAZOOKA AIRSOFT RIJUIN 0,43 / MOD. BR-043. 

Here you have a bazooka manufactured by Apple Airsoft 

6mmProShop Full Metal 1:1 Scale Airsoft WWII M9A1 Bazooka Grenade Launcher