Not In Mixed Company

"Not in mixed company..." Something I heard one of my grandma's say a lot, a long while back. I don't remember which grandma or what she was talking about specifically the first time I heard it. Really heard it. But it was said so often I begin to wonder its meaning. Of course, I knew what the words meant but I also knew I was missing context. So, I started paying closer attention. Noticing when exactly it was being said and who it was being said to. Watched everyone's facial expressions. Noticed any emotions spoken, shown or expressed. Body language was usually included. Changes in tones. Differing inflections. All told a story. Helped to draw some kind of picture. It all began to make sense, not in mixed company.