The Smoke Monster is a living cloud of smoke only known for killing and destroying all life around its area. When Mike was trying to buy a can of soda, the Smoke Monster came out of the can and saw Mike as a threat. Mike casually walked away. Turns out the Smoke Monster was trapped in the soda can for 100 years before Mike opened it out.
When the Smoke Monster went after Mike at his house, Mike got annoyed by the monster and grabbed his vacuum, sucking the monster up. It is currently still residing in the vacuum.