Baby Signing - what is the sign for nappy needs changing

[chocchipcookie]

And is different for a wet nappy/dirty nappy.

Thanks!

Cant you just make them up?

I am going to teach my baby signing so i'd be interested to know if it's a proper language or you just make up your own gestures. Sorry for ignorance!

here's a link for signs

bsl

bbc signs

Thanks!