Adventure Time - Season 3

After a deer knocks him unconscious and breaks his legs, Finn wakes up from 6 months sleep to find that the Candy Kingdom is deserted and Jake has gone insane from when he got hit in the head and thinks everyone is doing a surprise birthday party for him, then Finn hears candy people in sewers and tries to go down there but has to escape from Jake because he thinks it's going the ruin the surprise.