You could answer him with a blank text, your avatar image would suffice for an answer!
Btw check his history, he's either a bot or a person who doesn't know English and for whatever reason he spams... why do people even do that? Did anyone tell them they can make money here by spamming but forgot to mention the merit system? Then again they might be spamming to boost their post count and then merit-trade.... whatever the case I'm sick of these guys, I think I'll start giving them negative trust in case they merit-trade in the future!