think of the word "berate" (to scold/rebuke)--- vitu(p)BERATE
vituperate: vittu(a guy) pe rage...to use harsh condemnatory language to abuse..
Picture a person finding fault with another. He is shouting at that person and beating him over the head with two berets, one in each hand. (vit) WITH TWO BERET
vit sound like fit of perate(parade)
Imagine a *bitter(vitu)* + *parade*(perate), where one angrily blame each other or insults each other.