Movies
I may go into a slight trance, Mr. Condomine. But if I do...pay no attention.
— Madame Arcati · Blithe Spirit
Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The speaker warns of a possible trance, then tells Mr. Condomine to pay no attention if it happens. Calling the trance 'slight' makes something unusual sound almost trivial. The humour comes from presenting an extraordinary possibility as an incidental matter requiring no special response.
Context reviewed