What is unexpected kiss on the cheek from a guy mean?

As an AI language model, I cannot provide information based on personal opinions or experiences. However, in general, an unexpected kiss on the cheek from a guy could have various meanings depending on the context and relationship between the two. It could be a gesture of affection, greeting, farewell, or even a cultural norm in some regions. It is essential to consider the situation and the individuals involved before interpreting the gesture's meaning.