At a certain point, Rogers seems to be singing gibberish - she is actually singing in Pig Latin. She had sung the song so many times during rehearsal that she began singing it in Pig Latin to relieve the monotony & amuse herself. Director Mervyn LeRoy liked the sound of it, so he had Rogers sing the last part of the song that way.
Les Troubadours du Roi Baudouin - Missa Luba: Sanctus
Missa Luba a.k.a. “that song from 1968’s If…” is a Congolese version of the Latin Mass.
In the 1950’s, Father Guido Haazen, a Belgian missionary in the Congo, created “Les Troubadours du Roi Baudouin”, a choir of Congolese children. From their improvisations, Hazen arranged Missa Luba, a composition that adapted the Latin Mass to traditional Congolese melodies and rhythms.