"An uncommon expression which has been derived from an extremely common one. A hint, bari bari has something to do with the common expression. Bari bari is the onomatopeia derivation of the verb 頑張る ganbaru to do one’s best, which most of you have probably (correction: must have) heard when watching a random anime. The actual verb which is used in this expression is bari bari suru. Officially, it is not a real verb but part of slang."