I think I have to go with this one:
To Have and Have Not (1944) Lauren Bacall & Humphrey Bogart
"I've Been Wondering Whether I'd Like It" Kiss - with Some Advice "It's Even Better When You Help"
She answered him after their first kiss: "I've been wondering whether I'd like it" - he wanted to know her reaction: "What's the decision?" - and then she give him a second kiss to get a better evaluation after telling him: "I don't know yet"; she recommended to her less-than passive partner: "It's even better when you help"; she then suggested as she left his room, speaking in a low purring voice: "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. You know how to whistle, don't you, Steve? You just put your lips together - and blow"