Yes. If your crush is sending you signals, showing interest in you, or if you two are involved anyways, you're all welcome to send them a friend request. But if your crush takes you too casually, or makes fun of you, think twice before sending a request to this person.
Your crush calls you a dude because they consider you their friend. They feel comfortable with you and like to hang out with you. If you want to take it a step further, express your feelings to him. He is already inclined towards you, and there's hope for the future.