This is a substitute term to more specifically describe a roller derby "Grandma". In the roller derby community, a "Slam-Ma" is a term used to describe a female skater whose daughter (who may also participate in roller derby) has a baby, thus making her a "slam-ma" as opposed to just a "Grandma".
"Hey Cora Nary, Oogie Boogie Brookie just had her baby, thus making Breakin' Zem Bones a new Slam Ma!" Slam-Mother
by Xombie Apackalipz September 27, 2012