It is a standard piece of equipment on mining freighters like Red Dwarf and they look a lot like portable missile launchers therefore named after "bazookas". They have be "cocked", which recharges the blast.
Three million years later, the Boys from the Dwarf would often use them as both defensive and offensive weapons.
The Boys from the Dwarf often use them as weapons. They were first used to hunt down the Polymorph in Series III and were later used against Hudzen 10 in that same series. It is from that episode that we learn bazookoids have a dismantler button which makes the device fall apart.
They are later used throughout the show and novels, used as protection against various GELFs and simulants. Bazookoids, as shown in "Polymorph", have a special "heat seeker" mode that makes them track down and target body heat emanating sources. This caused problems as a misfire spun around and started chasing the Cat, leaving Kryten and Rimmer alone as they are mechanical and hologrammatic respectively, but causing the Cat to have to perform an extraordinary feat of acrobatics and quick thinking to avoid being blasted.
There is also another smaller laser gun, much like a small rifle or large pistol, that is used by the crew in various episodes. It is unknown whether or not this was also meant to be a mining device. Bazookoids, as shown in "Stoke Me a Clipper", can fire both live and dud ammunition. Lister has also used one to dig Starbug out of the dirt of an asteroid in "Psirens".
Much to the dismay of the Red Dwarf crew, a great deal of threats can withstand bazookoid blasts such as the Mutton Vindaloo Beast, the Unspeakable One, Hudzen-10, Simulants, and some GELFs (Kinitawowi will only be stunned if shot), and the Fecal Beast.