Series 1, Episode 13
Boone accompanies Locke on another venture into the jungle to figure out how to open the hatch they have found buried in the ground, but things turn out bad when Locke knocks him out and ties him up. The back story is Boone's relationship with his sister, the annoying Shannon and how he paid off her bully boyfriend to split up with her.
Back at the island, there is a humourous moment when Hurley steps on an urchin and asks Jin to pee on his foot; and Sun makes a mistake when she acknowledges some dialogue with Kate - giving the game away that she understands English.
Towards the end, the episode chucks up one helluva OMG moment!!!