Jb hates having his nappy changed, as soon as the nappy comes off the hand goes on the willy and if its a bit of a poo exppolsion this can be super messy!
Hand him two things...one for each hand.
Blocks to bang together or something hanging him over his head for him to try and grab.
It may distract him long enough to get the nappy done.
My DS (19 months) does the same thing and as soon as I start I say "right, can you show me your ears", and he'll put his hands to them, and then I go through eyes, mouth, teeth, nose etc. This generally keeps his hands busy long enough for me to clean up. If your DS is at that stage you could try that.
Don't worry - Sam's two and only knows his nose as well. He'll do more body parts for day care, but the only one we get consistently is nose.
I'd go with toys. Vary them. Something he's unfamiliar with or hasn't seen for a while. We had the same issue - and would often hand him a tube of cream from the nappy change supplies. A nose bulb aspirator thingy was great for a while (but make sure it's an unused one as it will likely go in the mouth). We just found it had to be something he wasn't used to having so it took his attention. His toys were a bit too familiar so didn't cut it.
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