OK, had the following conversation with DS (9) today:
DS: "Is penis a rude word?"
Me: "no, why?"
DS: "X made it up that I said it today and the stand in teacher told me off as it's a rude word"
Me: "well the word isn't rude, but depending on how you said it - it may have appeared rude"
DS: "I just told you I didn't say it"
Me: "if you called someone a penis it's rude because your calling them names"
DS: "I didn't say it"
Me: "If you said my penis hurts, it's not rude but it is something you should say in private"
DS: "I didn't say it"
Me: "what happened then"
DS: " I told you, X told the teacher I had said it and the teacher told me off as it's a rude word"
Me: "did you tell teacher you didn't say it?"
DS: "yes, but she said I did because X said I did"
Ignoring DS version of events as I do only have his side of the story AIBU to think a teacher shouldn't be telling a child the 'word' penis is rude?