2x27 - The Suite Life on Deck

Centuries in the future, Starship Tipton resident prankster Zerk (Zack's great-great-great-great-great grandson) plays a joke on feuding aliens and because of it, they vow to destroy the starship. The kids must travel to the future to save their descendants and fix the problem before it's too late. Meanwhile, London discovers that she has a great-great-great-great-great grandson, Rome, and that the Starship Tipton belongs to her family.