Dinosaurs From Space
After some intergalactic police aliens — who look like turd-shaped dinosaurs — zapped a criminal who fugitive’d his probe hole to Earth, they forgot to retrieve a proprietary energy necklace and laser blast cannon (one powers the other).
A direction-less teen named Billie, who always seems to have THE LAW breathing down his neck, finds the ray gun and figures out how to use it to get back at those who wronged him, like those local bullies and that !@#$% mailbox, whose just been asking for it.
Every time Billie uses the weapon, though, he changes into a green-faced ghoul with stoned eyes and short yellow fangs that could act as teeth should he desire some beef jerky or some other chewy treat. Speaking of, back in outer space, the aliens are being chewed out by their boss for leaving the gun behind. This is done in an upper atmosphere language I have yet to master.
Billie, having some fun, blasts stuff like it wasn’t against the law, even blowing up a billboard advertising the Star Wars (1977) movie. Priceless. But the fun can’t last forever; The aliens re-arrive, and in a moment of pure irony, blast Billie with a ray gun of their own. The light blue and pink beams may not look very harmful, but they ARE. May Billie rest in pieces.
Laserblast (1978) is classic cheeseball sci-fi that wants to be serious, but falls short by a few light years. A suggestion would be to try a more manly colored ray beam next time.