Soulja Boy’s friend took a bullet for the rapper on Friday. The “Crank That” singer’s pal Killa J was shot in the arm outside of a Hollywood recording studio where Soulja Boy and friends were celebrating his 26th birthday party, TMZ reported. The rapper — born DeAndre Cortez Way — and his entourage noticed a black SUV waiting outside the studio for hours, when Killa J decided to go outside and see what was going on, according to the gossip site. It is reported that the four men in the vehicle asked specifically for Soulja Boy and demanded he give up his Gucci bag — where he often keeps loads…