Anticipatory socialization refers to someone adopting the standards, values and social norms of a group they are not a part of to gain acceptance. Robert K. Merton, a sociologist, defined this phenomenon in 1949.
People practice anticipatory socialization in the real world every day. For example, medical students model the doctors they following and law students model the lawyers they follow. This is also true for those people seeking entry into a specific type of church or a Mormon preparing for missionary status. This allows people to integrate into a world that they are not used to by spending time with those already in the world they seek to become a part of.