neuralyzer

(noun) AKA flashy-thing. A fictional gadget from Men in Black that allows one to erase another's short term memory and replace it with spoken words similar to post-hypnotic suggestions.

Sometimes misspelled as neuralizer.

Kay: All right, Beatrice, there was no alien. The flash of light you saw in the sky was not a UFO. Swamp gas from a weather balloon was trapped in a thermal pocket and reflected the light from Venus.
Jay: Wait a minute. You just flash that thing, it erases her memory, and you just make up a new one?
Kay: A standard issue neuralyzer.
Jay: And that weak-ass story's the best you can come up with?