Be Careful What You Fish For (S10E14)

When Peter and the guys try to salvage a sunken Mercedes-Benz, Peter half-heartedly promises a favour to a helpful dolphin. Soon the dolphin moves to Quahog, outstays his welcome at Peter's and moves into Cleveland's house across the street. Peter tries to reunite the dolphin with his ex-wife in the hope that he will return to the ocean, but his plan backfires and the whole dolphin family moves into Cleveland's. (BBC)