No coarse language of any kind, which my parents themselves didn't use. Nor any racial slurs, which likewise were never spoken at home. I'm not sure I was ever explicitly told not to use certain words, but somehow I knew. Except for one time --
Story: we were coming back from a few weeks on Cape Cod the summer of 1966, when I had turned 17 and had just gotten my driver's license in our home State of New Jersey. As we got onto the Connecticut Turnpike my father pulled into a plaza for gas, and shocked me by saying I could drive the car myself.
It was a damn Chrysler Imperial, a huge boat of a car, the biggest there was on the road in those days, that I had never driven before. But he apparently thought the open turnpike was a good way for me to learn, even if the speed limit was 65 mph.
So off we go, my father sitting up front with me, my mother & sister in the cavernous back seat. Everything's going fine, until we came to the second set of toll booths and I started to slow down. Suddenly the brakes started scraping loudly. In those days drum brakes didn't last more than about 25,000 miles, and there were no audible wear indicators. When the brakes went, they went, all at once and without warning, and this car was 2 years old.
I knew what was happening, but I didn't know what to do about it. In my near panic I started swearing, something I rarely did, and certainly not in front of my family. Not really bad, but a lot of "goddams" and "hells" but no "F" bombs.
Nevertheless, as we exited the toll plaza, I realized the car had suddenly become totally silent. My mother & sister were no longer chatting in the back seat, and my father wasn't speaking, either. I could see my mother's shocked look in the rearview mirror. Nobody said another word for nearly an hour, the inside of that car as silent as a tomb.
When we got home (and my father took the wheel again when we got off the turnpike), he took me aside, and told me to NEVER use that kind of language in front of my mother & sister again. And I never did. To this day I very rarely use vulgar language, even after 25 years in the US Army, when I didn't use it either, something of an exception.
It wasn't how I was raised, and frankly I consider recourse to such curse words a weakness. And words of a negative racial or ethnic nature totally unacceptable. They weren't spoken in my home in the 1950s, and I see no reason to use them today. And except for that one time on the road, I never had to be told what words were banned -- I just knew.