MTO EXCLUSIVE SHOCK PIC: Rihanna's BABY BROTHER Is Photo'd . . . GETTING IT IN . . . With An OLDER CHICK!!

April 30, 2012: Rihanna's little brother Rajad is only 14 years old . . . and he's already PULLING CHICKS . . . 18 and over. Peep the pics we got of him 'DANCING' with that much older teenage girl . . .