Is there ever a reason to say to your DS...

[Hardrockhallelujah]

... If you don't stop that now , I'll smash your face in?

No

I have said it to my kids but it is always when they have been teasing me and everything is lighthearted - and they were over 12,

Can't imagine it ever being appropriate any other time though.

Ok thank you - this is what I thought too.

No.

I suppose that if it were grossly exaggerated and clearly a joke, it might be OK, but I'd still find the language too aggressive. Unlike 'I'll rip your arm off and beat you round the head with the soggy end' which I find OK as it's clearly absurd and would never be said as an actual threat, unlike example in OP which might be.

So, your OH said this to DS? 'Smash your face in' - it's very graphic, isn't it?

No. I do make absurdly violent jokey warnings but that sounds very aggressive/meant to be intimidating.

No.

As other posters say, I might possibly make a really exaggerated joke which they know is just ridiculous. But no, never 'smash your face in'.

Doesn't sound like a 'joke' phrase to me!

How about "I'll cut your head off and put it on a stick" ? a'la olde London Bridge style

No!

I have heard similar phrases barked by other parents in public though.

Ha! Just me then! Like I said it was very much in jest with no malice and the kids aren't little.

That's a big assumption, tallwivglasses No, I heard someone say it earlier and it was bothering me.

Like meditrina and HippoCritic, if I were to make a joke threat I'd make it absurdly violent partly to signal that this really is a joke, partly because there is no point in a joke that isn't funny. |"I'll smash your face in" simply isn't funny. Unlike the Wodehouse phrase "I'll pull your head off and make you swallow it".

Actually I do say it to DS as a joke because we're both big Morecambe and Wise fans and that's one of Eric Morecambe's old catchphrases.... grabbing hold of the lapels and saying 'I'll smash your face in'.

As I said it's a joke and the response I get is 'You'll have to get a step ladder first' (DS2 is 14 and 5ft 9 andDS1 is 6ft3)

It all depends on how it's said. If it's said in an aggressive way to ds then I'd say it is inappropriate. But if it's said in a way that's know to him as jokey then I think it's fine.

It depends on the person and how colourful their language is the rest of the time. Some people just speak like that but they are not actually threatening people as in the child would not take it literally. It doesnt sound nice though and it does depend on how much anger was behind the threat. I normally threaten a crack on the arse as it doesnt sound as violent

Jokey threats by me are usually throwing out the window (absurdly OTT) or a smack on the bum (not particularly violent).
Other threats of violence are more of the you would deserve a smack for that.

Smack your face in sounds very threatening and too real.

The answer to this is all about context. Me grabbing DS by the lapels, looking at him over the specs Eric Morecambe-style, putting on the funny voice and saying 'I'll smash your face in' ... is a joke. If it's some angry red-faced bloke saying 'I'll smash your face in' as a serious threat... not acceptable.

Depends how it's delivered? I say all manner of 'terrible' things to ds, his favourite is when I threaten to rip off his leg and beat him with the soggy end

I couldn't see the context as heard through the window. When I looked out, I could see a man and a little boy walking down the road. It bothered me all evening...

No, not in a serious context!

However I am often (jokingly) going to beat my children up if they don't do what they are told.
I actually do (play) beat them up which is easy with the youngest but the eldest is 14, nearly my height and strong so it's becoming more of a struggle. I have to 'do him' by stealth!

If it's a quotation, as with Cogito, then it could well be funny; the joke is in the reference.