Mike likely experienced an alcohol-induced blackout, or as it commonly referred, he was "blackout drunk." This state can occur when a person drinks more alcohol than their body can safely process, temporarily interrupting the brain's ability to retain memories, resulting in a form of short-term amnesia. During these episodes, the person is still conscious, able to walk and talk, therefore it can be difficult for others to recognize the severity of the situation. After reaching this state of intoxication, the person will likely eventually pass out or fall asleep. It's only upon awakening that they realize they cannot remember much of the previous day's/nights events, often to their chagrin when embarrassing stories are related to them from friends and family.