Each song, on Thursday, was translated into Russian and then back to English, resulting in completely different lyrics.
Lovato kicked things off by performing "Walking on Sunshine" by Katrina and The Waves which became "Now Mom's in the Sun Now."
"Now mom's in the sun now, water/ A quality's poor!" Lovato sang using the new translated lyrics.
Fallon performed "Someone You Loved" by Lewis Capaldi which became "All My Favorite Carpets." Lovato ended things with a performance of her own song "Sorry Not Sorry" which became "Apologize to My Infant."
"I will apologize (to my infant)/ I was affected by the twisting of boards/ I think it's hot when I'm on fire," Lovato sang.