Mike was from southern California and spoke with pretty broad surfer-boy dialect. I think that’s where “bra” originated, Evelyn Jane Saungikar.
He was using it well before it became widely popular. I’d never heard it before. Plenty of his other usages were odd to me too.
If amuses me that with his laid back surfer personality, he went on to become a brigadier general and then an influencial defense contractor.