I notice a yellow Nerf gun–like toy on the couch inside the firehouse.
He shot at them with his Nerf Gun, assaulted them with racial epithets, and worst of all, he stole their snacks.
1955, in nerf bars, hot-rodder slang for "custom bumpers;" from slang verb in auto racing (1953) meaning "to nudge something with a bumper in passing and knock it off course;" ultimate origin and signification unknown.
As a trademark name for toys made of foam-like material for indoor play, introduced 1970 (Nerf ball). By 1995 this had yielded a verbal sense of "to make less effective" (as a Nerf basketball is softer and lighter than the real thing).
To bump a car out of one's way
[1950s+ Hot rodders; origin unknown]