ask cartwright

Does anyone remember a scene where Bob visits a place like a sanitarium or hospital, and he wanders into a room where there is a guy who has an imaginary friend called 'cartwright'? In the scene the old guy gets angry at his 'friend' and shoots him. Bob Hope escapes from the room and tells a passing doctor who says of the old guy something like 'oh he's harmless' to which Bob Hope says 'I don'tknow about that - ask cartwright..' I have been trying to find the movie this scene is from, can anyone help?