In a Family Guy episode entitled "The Simpsons Guy," Peter, Lois, Chris, Meg, Stewie, and Brian take a road trip and find themselves in Springfield, face to face with their arch-rivals.
Homer, who refers to the Griffins as "albinos," welcomes the strangers, and the two families hit it off.
According to a synopsis obtained by Entertainment Weekly, Stewie takes a shine to Bart and his pranks, while Lisa tries to find something Meg is good at. Marge and Lois "do some bonding," while Peter and Homer have an argument over beer labels.
As EW notes, Simpsons voice actor Dan Castellaneta (Homer et al.) had a cameo in a Family Guy episode last year, and MacFarlane himself guest starred in The Simpsons' season 24 finale.
"The Simpsons Guy" is set to air on Fox in the fall of 2014.
[screengrab via Family Guy]