Peter: Alright, so Psalms 137: Basically, it's about the Israelites being sad and homesick while they were in exile.
Brian: So it's like that episode of The Simpsons when they all go to Shelbyville?
Peter: You got it, Brian. Except it's much sadder because they don't want to ever go back home.
Lois: That's really heartbreaking.
Stewie: Yeah, and then they talk about how they would be happy if they could just forget their troubles and just dance and sing.
Chris: Like when we went to the Spice Girls concert?
Peter: Yeah, that's kind of the idea. Then they talk about how they would never forget Jerusalem and the things that happened there.
Brian: So it's like when I go back to my hometown and remember all the good times?
Lois: Something like that, yes.
Stewie: And then they talk about how they would be willing to do anything to make sure Jerusalem remains a powerful city, even if it means taking revenge on the people who destroyed it.
Chris: Like when I got revenge on that kid who stole my Game Boy?
Peter: Yeah, kind of like that.