With ironic, or not, reference to the rhetorical skills and intellectual abilities of Barrack Obama, a person who boasts about their ideas and accomplishments. Depending on the context, the term is used ironically to contrast the "oboomer" with Obama, or to suggest that Obama is himself an "oboomer."
Bob never stops yapping about the great things he has done, and and is going to do. He thinks he is soooo smart.
Yeah, he's a real oboomer.