Family Guy - 5x18 - Meet the Quagmires

Death grants Peter's wish of going back in time to be 18 again just for one night so that he can sow his wild oats. In 1984, he bails on a date with Lois to go to a bar and make out with a movie actress, but when he returns to the present, he discovers that he is now married to the former starlet and Lois is with Quagmire.
Source: Fox