In two preview clips released by Fox, the pop icon puts on a concert (clad in meat-inspired hummingbird and Grammy dresses) urging Springfield's citizens to appreciate each other for what makes them unique.
She sings: "When they're young, all little monsters learn that they are scary. Ugly, stupid, shunned by cupid, overweight and hairy. But every monster needs to find that secret deep inside. That transforms Dr. Jekyl into sexy Mr. Hyde. All my monsters are beautiful ... Monsters don't need implants or a bitchin' monster car, monsters only need to love the monsters that they are."
Later, she tries to cheer up a down-in-the-dumps Lisa, who's been outed as the author of positive posts about herself on school's blog, with a personalized flash-mob. "Now listen, if that didn't fundamentally change who you are, I don't know what," Gaga quips.
Check out Lady Gaga on "The Simpsons" Sunday night at 8 p.m. ET on Fox.