STANLEY: You see, under the Napoleonic code – a man has to take an interest in his wife’s affairs – especially now that she’s going to have a baby.
[Blanche opens her eyes. The "blue piano" sounds louder.]
BLANCHE: Stella? Stella going to have a baby? I didn’t know she was going to have a baby!

– Tennessee Williams

A Streetcar Named Desire, Scene 2. Stanley plays the part of the dominant male as he invokes the Napoleonic code, saying that whatever property his wife owns he owns too. The rising volume of the blue piano music is used here to signal the possibility of conflict.