Maybe just whistle

Slim: (She holds up the bills again.) Uh, sure you won't change your mind about this?
Steve: (affirmatively) Uh-huh.
Slim: This belongs to me and so do my lips. I don't see any difference.
Steve: Well, I do.
Slim: Okay. You know you don't have to act with me, Steve. You don't have to say anything and you don't have to do anything. Not a thing. Oh, maybe just whistle. (She opens his door and pauses.) You know how to whistle, don't you, Steve? You just put your lips together - and blow.