I'll just say, "Hola, who's there?" Also, if it turns out to be a ghost I'll just have a BOO contest with him, and when I beat him he'll have to leave haha.
Gurtthak your spanish is kind of messy, but don't worry, it gets better with practice i would say: HOLA, HABLAS ESPAÃ'OL O SOLO SABES DECIR HOLA...(it's kind of rude)
this is an example of exactly what I would do... http://wongkk.com/images-3/answers/ans05b/coin01.jpg" alt="http://tbn0.google.com/images?q=tbnhttp://wongkk.com/images-3/answers/ans05b/coin01.jpg" />
mostly because I'd be freaked out about having a random mexican in my house.