Green’s Dictionary of Slang

(US black) one’s grandmother.

1946		C. McCullers Member of the Wedding 51: When Berenice said we, she meant Honey and Big Mama.
1954		(con. 1920s–30s) J.O. Killens Youngblood (1956) 6: She sat on the back porch listening to her Mama and Big Mama talk.
1965–70		in DARE.
1999		Reading Online 🌐 The entire family in the story is ‘in a stew’ as they frantically attempt to prepare a birthday dinner by cooking grandmother’s (referred to fondly as Big Mama) favorite dish, oxtail stew.
2002		www.meshells.com 🌐 I learned the tradition from my grandmother when I was thirteen and in trouble. ‘Boudreaux,’ Big Mama says to me. ‘You are finding too much trouble.’.