A coma is a profound state of unconsciousness. A comatose person cannot be awakened, fails to respond normally to pain or light, does not have sleep-wake cycles, and does not take voluntary actions.
After being released from prison and left feeling doubtful towards the concept of karma that had dominated his life for the past three years, Earl ran out into the street. He was immediately knocked down by Billie Cunningham and left in a comatose state. Billie, upon realizing what she had done, got out of her car and was herself run down and comatose ("Bad Earl").
Once Randy, Joy, Darnell and Catalina had worked hard to cross items off his List for Earl, he awoke from his coma after having a sitcom-like dream, "The Hickeys", involving him and Billie. He decided to seek her out, but found she had already left the hospital and was no longer in a coma ("Killerball").