Was he the A's ball boy and some of the players invested in him?
I had no idea:
"Before becoming a global music icon, MC Hammer (born Stanley Kirk Burrell) worked as an 11-year-old batboy and clubhouse assistant for the Oakland Athletics from 1973 to 1980. Team owner Charlie Finley hired him after spotting the energetic kid breakdancing and selling baseballs in the stadium parking lot.The A's players affectionately nicknamed him "Little Hammer" (later just "Hammer") because of his striking physical resemblance to baseball legend Hank "Hammerin' Hank" Aaron. Beyond just handling bats, the charismatic teen became Finley's close associate, and would spend games in the owner's luxury box calling into Chicago to relay live play-by-play."
That's how he got his name. That's cool.