The Freeze Ray is a secondary powerup found in Dr. Lunatic and Dr. Lunatic Supreme With Cheese. They look like toy guns with small dishes at the end.
When Bouapha picks up one of these Freeze Rays, he is able to fire five frozen bullets.
When fired, a frozen bullet will fly through the screen until it comes to collision with a monster and freezes it, (this weapon causes no physical damage or harm) or it'll disintegrate into nothingness after three seconds.
While Bouapha Rages while holding a Freeze Ray, frozen bullets will fly in seven different directions, freezing whatever monsters stands in its path. The Rage effect doesn't deplete the ammo of the weapon nor does it replenish it.
A few non-playable characters use this in the game, the most prominent examples of NPCs using such weapons however, are Frostbites.