Bongolese - that weird language Bono sings in sometimes... in other words, when he mumbles/screams stuff you just can't understand...
classic example is Electric Co... WTF is he singing right before the fade out? I messed with that a bit at home and I think I have figured it out... same with the first words in "If You Wear That Velvet Dress" (which, BTW, are not X-rated, contrary to popular belief!), and the song Boomerang II (which is confused because everyone who is singing on that song (at least 3 people, I think four) is singing different words!!! )...
Best example is the song "Elvis Presley and America", where he was just making up stuff as he went along....