Frustrated 5yo - stomping feet

[LillyBugg]

How do you deal with this behaviour? DS does this when he doesn't want to do something I ask, or a toy doesn't quite work how he hoped. He grits his teeth, stamps and kicks, holds his arms around his body tightly. It's clearly absolute frustration but I don't know how to help him with it?

I've tried explaining it doesn't help, I've said grown ups don't do it, I've encouraged using words (but honestly when I'm cross I will swear under my breath, what words can I actually suggest to him that will satisfy the frustration?!). I just want to help him deal with this emotion.

Why don't you want him to do it? He's little, he doesn't have to use words like adults if it doesn't help. I encourage my 3 year old to stomp his feet or do a big breath out it he's upset. If he's not hurting anyone why does it need to be different?

Because I don't think it's okay that when I say 'please go upstairs and do a wee' that he stamps his feet up and down, growls at me and grits his teeth?! Surely that's not okay. He's five, I really don't think it's okay to be stamping feet at five. Maybe I'm wrong...

Just ignore it. He will stop doing it eventually.

To be fair I haven't tried totally ignoring it. It is really hard to, especially when he's doing it in front of other people. But I guess my reaction could be encouraging it.

I think it's pretty normal at 5. SDC have done it to me - I think they think they are being "scary" / trying to get me to back down but I just look at them with neutral/almost bored expression & repeat what I've asked them to do.
It's got less as they realised it doesn't get a response. They are probably trying to exert control / learning emotions so I let it slide. I don't accept violence/slamming doors though!

Ok well I can definitely try ignoring. All suggestions welcome!