Green’s Dictionary of Slang

Bahama momma n.

[proper name Bahamas + SE momma]

(US black) a fat, unattractive ‘black Mammy’ stereotype, supposedly typical of the West Indies.

[US]E. Folb Runnin’ Down Some Lines 145: Other terms for obese women, Bahama momma and Judy with the big bootie [...] suggest excessive girth and unattractiveness.
[US]R.C. Cruz Straight Outta Compton 26: Your big, fat Bahamma momma ain’t doin’ nuttin’ but sitting on her black behind.