Don't examine this too closely.
Said by producer Donald P. Bellisario on March 17, 1990 at a sci-fi fan convention in response to a persistent fan with very specific questions about the way things worked on Quantum Leap, a series Bellisario had produced.
Bellisario's Maxim is an unashamed admission of handwaving details unnecessary to the enjoyment of a show, and an exhortation to not let the obsession with those details get in the way of the story. Implicit in the Maxim is a request to understand that the story is being told by a small production team that (due to the limitations of the medium) has to work quickly, with a limited budget and tight deadlines, and has to dodge Executive Meddling, all while trying to turn out the best product it can.
Frequently quoted in various fan communities in response to excessive Fan Wank, and to arguments about Canon, Fanon, Word of Dante, Word of Saint Paul, and Word of God. At its worst, it's misused to cover up cases where a creator genuinely did a bad job. As well as personally undesirable details, like someone having a minority sexuality which could lead to unfortunate implications.
Sometimes expressed as "Leave your brain at the door" (i.e. upon entering the theater).