Unless you saw a different version other than the one that aired in FOX November 11th 2011 or the one that's available online, Peter doesn't sing anything to Ryan Reynolds or to anyone in Stewie Goes for a Drive.
If you're American, it's season seven; if you're British it's season eight. The episode's called 'Family Gay'
Season 3, episode 21: "Family Guy Viewer Mail #1"
It's from Stewie Griffin The Untold Storyspecifically the episode Bango Was His Name-O that aired as the Season 4 finale.
Season 8|Episode 11 Dial Meg for MurderJoe also arrests her and presumably takes her to jail at the end of Season 4|Episode 27 Untitled Griffin Family History
Season 4|Episode 5 The Cleveland Loretta Quagmireand then again as 'Irag Lobster' in Season 10|Episode 4 Screams of Silence: The Story of Brenda Q
Season 4|Episode 27 "Griffin Family History"
'Griffin Family History' Season 4 Episode 27
If you're American, it's season seven; if you're British it's season eight. The episode's called 'Family Gay'
The Griffin clan head south in the episode 'To Love and Die in Dixie' (UK Season 4/US Season 3).
Season 3, episode 21: "Family Guy Viewer Mail #1"
Season 2|Episode 1 Peter, Peter, Caviar Eater
It's from Stewie Griffin The Untold Storyspecifically the episode Bango Was His Name-O that aired as the Season 4 finale.
Season 8, ep. 11, "Dial Meg for Murder"
Season 8|Episode 11 Dial Meg for MurderJoe also arrests her and presumably takes her to jail at the end of Season 4|Episode 27 Untitled Griffin Family History
Season 4|Episode 5 The Cleveland Loretta Quagmireand then again as 'Irag Lobster' in Season 10|Episode 4 Screams of Silence: The Story of Brenda Q
family guy season 8 episode 15 "Brian Griffin's House of Payne" total episode 141
Season Six | Episode Three Believe It or Not, Joe's Walking on Air