The Griffin children sing goodnight to Peter, Lois, Brian & Mr. Weed the lovable little pot leaf....who likes little children.
So Long, Farewell performed by the Griffin family and Mr. Weed in Mr. Saturday Knight. The song was originally from "The Sound of Music". When those at Family Guy first requested the rights to the song they were told they could only use the song if they left it unchanged. The decision was made that the song was random enough to be placed in the episode unchanged.
Lyrics
Chris, Meg & Stewie: So long, farewell, au revoir, auf wiedersehen
Meg: I'd like to stay and taste my first champagne, Yes?
Peter: No! NEVER!!!!
Chris, Meg & Stewie: So long, farewell, auf Wiedersehen, goodbye
Chris: I leave and heave a sigh and say goodbye -- Goodbye!
Mase: Dat nigga stoled my cow
Stewie: The sun has gone to bed and so must I
Chris, Meg & Stewie: So long, farewell, auf Wiedersehen, goodbye, goodbye, goodbye, goodbye
Peter, Lois & Mr. Weed: Goodbye