umm...i would probably freak out (of excitment) but then i'de go to reality calm myself and be like what r u doing here...cuz that would be random if he endedup in my house???
I would say welcome, invite him in and ask him as many questions I have in mind about him and I would ask his number and ask him to perform my favorite song of his and I would take some shots of him with me and bid him bye
i would probably be speechless and faint i would also show him my room full of (him) Justin Bieber and then faint again and get his autograph and take a bunch of pictures with him!! I <3 Justin Bieber