It's possible it's:
* A misspelling of a real phrase: Check for similar sounding words or phrases in the language you're interested in.
* A specific slang term in a particular region or community: If you heard it from a friend or in a specific context, try asking them what it means.
* A nonsensical phrase used for humor or emphasis: Sometimes people use made-up words or phrases for comedic effect.
Without more context, it's difficult to determine the meaning of "oga boga".