A grandmother pretends she doesn’t know who you are on Halloween.

The line plays on the affectionate, indulgent role of a grandmother: she is so committed to a child’s fun that she will “pretend” not to recognize them when they are costumed on Halloween. The humor comes from reversing the usual dynamic—children often disguise themselves, but adults typically see through it; here, the grandmother colludes in the fantasy. In Bombeck’s domestic comedy style, the joke also hints at family intimacy: only someone who knows you well can convincingly act as if they don’t. The quote celebrates small rituals of family life and the generosity of adults who sustain children’s imaginative worlds.