An environment for creative collaboration is significant for enhancing human communication and expressive activities, and many researchers have explored different collaborative spatial interaction technologies. However, most of these systems require special equipment and cannot adapt to everyday environment. We introduce Second Surface, a novel multi-user Augmented reality system that fosters a real-time interaction for user-generated contents on top of the physical environment. This interaction takes place in the physical surroundings of everyday objects such as trees or houses. Our system allows users to place three dimensional drawings, texts, and photos relative to such objects and share this expression with any other person who uses the same software at the same spot. Second Surface explores a vision that integrates collaborative virtual spaces into the physical space. Our system can provide an alternate reality that generates a playful and natural interaction in an everyday setup.