I'm with OG on this. I tried oysters when I was a teenager. They didn't seem to taste of very much, although the sauce was pleasant, but I found the oysters themselves repulsive. Nowadays I find flesh of any kind repulsive to eat, but even when I was a meat-eater, oysters were yuk to me. I think they are a bit like Marmite, you either love the taste or you hate it.
Back to the original question, I always heard it was pork you shouldn't eat if there was no R in the month, but maybe that was just in the days before refrigeration.