A reference to the character of Boo Radley in the novel "To Kill a Mockingbird", a "Boo Radley moment" is when a person is astonished at the sight of something or someone excessively strange and/or rare.
(Seeing a recluse emerge from their home after a prolonged period of time)
Man: *stares blankly, mouth open*
Recluse: Having a Boo Radley moment, are we?
Child: Are we there yet?
Mother: No, not yet.
Child: Why not?
Mother: Because your whore of an Aunt forced your Uncle to move out to Jabip so he can't see his family anymore.