Rocco whispers to Nora

Robinson probably said, "Bergman was better in Casablanca than you were in To Have and to Have Not", or
"I am supposed to be talking to you dirty, sweet-cheeks".

Of course the censors of the day wouldn't allow any blatant sexual acts to be spoken, but what they did is far more effective and used in other movies to the same effect. By not knowing it allows the viewer to go to wherever their imagination limits them to go and doesn't offend anyone in the process. Some imaginations can go much further than others, especially then, when everything wasn't as open as now. It's a win win, it's still being wondered about today so it worked. What's in your mind can be worse than the reality... I think everyone can agree it was an invitation of some sort..

There is so much written about this that I am surprised only one poster knows about at least one version of what he said.

Huston told Robinson to whisper something, for want of a better word, dirty to Bacall, in an effort actually offend her. However he also realized it might make her laugh.

we will probably never know and that just fine. We don't need to know.

It could have been anything from the food here sucks to a dirty joke or something actually related to the film like why don't you take Gaye's place. I bet your a better *beep*, or lay or whatever.

What ever it was it was meant to be sexual and that is conveyed better than if we actually heard what it was. Our dirty little minds can do much better than Robinson did. A viewer specific sexual come on.