No, I'm saying that if you get 1 Run Batted In, you got 1 RBI.
If you get 2 Runs Batted In, you got 2 RBIs.
It doesn't matter what letter come after the first letter of each word. The abbreviation is "RBI". So the plural of the abbreviation "RBI" is "RBIs". It's like any other abbreviation.
Also, "ribbie" is just pronouncing "RBI" as a word. But you said "3 ribbieS", not "3 ribbie"?
"Ribbie" is saying "RBI", so "Ribbies" is saying "RBIs" . So you should say "RBIs" ("ribbies").
I can't even believe that people ever considered saying 3 RBI. No one ever used to say it, so where did you get it from?