There seems to be a lot of discussion about Tourette"s on the interwebs lately, because of the outburst at the BAFTA's.
I'm not sure if he's for real. It's not a word I've ever had the urge to say.
However, I do know why we say Fuck a lot.
N sounds push behind the upper incisors, they are a common problem. But the rest of the N-word is not helpful for me. It interrupts the motion. "No no no no no" works much better.