I often have to search a second time with a category:
In the case of FC and FD, I got way too many results (including “Feeling Cuddly”; no thanks).
But it was in a used car ad, so I tried “FC FD car” and learned that “FC was the chassis code name for the white RX7, FD was the yellow one”… nope, this wasn’t even a Mazda.
Finally tried “FC FD car slang NSFW”, and found out the car I was reading about had FC: “Fücking Corrosion” and FD for ”Fire Damage”.
Maybe that’s why they didn’t want to make it too obvious.