"Yes, fine, clearly I kidnapped you in the middle of the night and brought you to my apartment, set you up in your own room, dressed you in my manservant's clothing and then rearranged your face to look like his and have a twisted sense of humor."
This was in no way Merlin. Even Merlin wasn't this stubborn, which said a lot. Arthur pointed toward the bathroom where there would be a mirror and less chance of being pitifully run at by someone who was 1/2 his size in body mass and not even in their right mind, or in this case body.