My cousin claims he was abducted by aliens last night. How can I convince him he wasn't?

My cousin came to the house today in a panic. He says he was abducted last night by aliens. I told him he was an idiot and he just said it really happened. He says they did weird experiments on him and then brought him back in his bed. I told him it was probably just a dream. How can I convince him he wasn't abducted? He is 14.