Stands for "Eat it", Nelly uses it often in his songs. Means that you are about to receive oral sex.
From Nelly's song: "My boo gives me head up in the bath tub... EI, EI."
A variation of "Bombastard"; a combination of:
Bombastic: Grandiloquent, pompous speech or writing
Asshole: A thoroughly contemptible, detestable person.
One who condescends and overuses grandiloquent, pompous speech or writing in an attempt to exert his/her intelligence over another's, particularly during a disagreement.
"I could give you the full context for how I happened across this quote, but proving you wrong would require me to dumb it down for you".
You sir, are a bombasthole.