Post and Telegraph Office

It's looked like this forever or for as long as I can remember.

An excuse to tell my only joke. A dog went into a Post Office.

Dog:   I'd like to send a telegraph, please.
Assistant:   Certainly, sir. What do you want to say?
Dog:  Woof woof woof woof
Assistant:   There's a minimum charge for 5 words. You could say Woof woof woof woof woof
Dog:   That doesn't make sense.