Where did you hear the term "Jebus?" I know that the neo-Nazi apologist (and onetime contributor to National Review) Revilo Oliver used to mock those who were "high on Jesus Juice." Then again, he also attacked Christianity as a "semitic perversion."
My former boss, a southerner, chronic mispronouciation.
I think the popularized usage comes from the Simpsons, in the episode where Homer becomes a missionary...