Green’s Dictionary of Slang

grits n.1

[lit. + fig. uses of SE grits, coarse oatmeal, a trad. Southern or black food]

(US black) any form of food.

[US]W.R. Burnett Little Men, Big World 183: ‘I just sit down and expect the grits to be on the table.’ ‘The what?’ ‘The food, the food!’.
[US]P. Thomas Down These Mean Streets (1970) 97: I [...] waited until she was in the kitchen getting some grits for her kid.
[US]‘Iceberg Slim’ Airtight Willie and Me 11: She gave you a buck for grits and greens.
[UK]R. Antoni Grandmother’s Erotic Folktales 152: ‘Time to hit the grits!’ So we all assembled weself around the big diningroom table.

In phrases

up in someone’s grits

(US black) of a man, having sexual intercourse.

[US]Ebonics Primer at www.dolemite.com [Internet] up in someone’s grits Definition: getting some from a female Example: Man, that girl is so fine I would not mind getting in those grits.