Season 2: Episode 10: Da Boom
Peter, warned about the end of the world by a giant chicken, forces his family to take cover in the basement for New Year's eve. They survive the nuclear holocaust, and with help of a Twinkie factory in Natick, they found New Quahog from the remnants of their lives. Peter is mayor of the new town, but when everyone gets sick of the lousy job he's doing, the Griffin family gets kicked out and heads for a Carvel factory. Meanwhile, Stewie, who has been mutated into an octopus, leaves behind eggs which hatch a whole bunch of violent clones that destroy New Quahog.