First everyone was saying it was his dad and we all know Shaggy, even if he doesn't have hits now, made a lot of money off of his hit songs in the past. That said Robb talks about living that life, selling dope, shooting at fools, etc. all the time in his raps. Where then if your dad was a multi-millionaire before you were even born (he's 17) that would seem pretty absurd. I really don't give a fuck, one of the top selling artists used to be a CO, but a lot of people still feel strongly about "keeping it real" in rap even though 90% of rappers were never what they spit about. Turns out it's his uncle though so who knows what's true or not. I don't care either way as long as he keeps putting out music I like.
The marines try to show off a higher standard, probably just bull shit for better advertisement though, to my understand in the army your judged by # of push ups, sit ups, and a two mile run as for the core is pull ups, sit ups and a three mile run.