It's not hard to become Gray's friend, nor is it easy. If you're a big fat cheater you can put in the code for all people to be your friend. But, if you're like me, you'd rather work from scratch and become his friend, right?
Gray likes eggs. Giving him eggs and such will make him like you more. If he says 'Sorry' at one point when you give him something, you know he's your friend. ^^ He also likes to see your dog and you get a glimpse of his happy face when you show him the dog. Just don't give him weeds, ok? Even if he is mean to you. When you're on your way to ultimate friendship with him, he'll ask you a question, and give you 3 choices. You can ask about Ann, animals, and something else I forgot. Lol.
If you have a kitchen and he's somewhat of a friend, give him an egg for the Stuffed Omelette recipe.