Question: what is the meaning of your joke

Jake Langham answered on 8 Nov 2017:

I’m not completely sure, it just makes me chuckle. Maybe the dog doesn’t understand that when you write down ‘woof’ they all look the same. Or maybe the postman doesn’t understand that 9 woofs is **completely different** to 10 woofs. Also, clearly the dog can speak english so why are they writing down woofs in the first place?!