How to answer this question?

A conversation that took place last week. 

William: 'Mommy, do you promise you won't get mad if I ask you this?'
Me: 'Um. OK.'
William: 'What IS a somamabidge anyway?'
Me: 'It's something some people say sometimes that is not very nice. And I never want to hear you say it to anyone, OK?'
William: 'OK. Are you mad at me?'
Me: 'No'.
William: 'Somamabidge!! Somamabidge!! Ha ha ha ha ha!!!'

Say it s-l-o-w-l-y, people. So-ma-ma-bidge.

As in, 'I want my father back, you somamabidge'.

This is a direct quote from that winsome fairy tale for the entire family, The Princess Bride.

William's version may not be an exact translation but it's close enough to give me the heebie jeebies thinking about him potentially going to school and saying it within earshot of his teacher. Who is a nun.

Back track six months. We are on vacation in Australia when William first lets loose with 'you somamabidge! He's laughing since it's obviously the funniest thing he's ever heard. Let's just say I did not react well upon hearing these words come out of my then five year-old's mouth. And of course, I immediately blamed his father.

Me: 'Did you hear Daddy say that?'

William: 'No. I heard it on The Princess Bride.'

Me: 'No you did not. You're not in trouble, I just need to know where you really heard it.'

William: 'Seriously Mommy, it was on The Princess Bride. Seriously!'

Me: 'OK, show me.'

He did. Well, color me seven different shades of shocked. (Apparently this movie was released in 19freaking87. Somehow it had passed me by completely.)

So now I just blame his father for putting it on the iPad for him to watch. But honestly, what kind of family movie contains this kind of language? Or is it not really considered bad language to call someone an S-O-B these days? Or is The Princess Bride not really a family movie? I mean, you don't hear the Scarecrow or the Tin Man screeching obscenities as they frolic down the yellow brick road, do you?

What. The. Heck?

My name is Inigo Montoya indeed.  Not suitable for
small children no matter how many sword fights there are.