NSFW message

When trying with a very basic model of a medieval castle, If I use a prompt with the word cliff, I get a NSFW message and the generation is aborted. If replace cliff by rock, it works. To the best of my knowledge of English, a cliff is a falaise (french for cliff).

I don’t understand what is causing this message.

Odd. I gave it a try and indeed I cannot get Diffusion to generate anything with the word " cliff " in the prompt. I can’t think of why that word would be a trigger. However I got this image by substituting the word “precipice” which it accepts. ???