flatbacking, n. — Green’s Dictionary of Slang

flatbacking n.

[the trad. ‘missionary position’]

(US black) working as a prostitute.

1990		S. Morgan Homeboy 4: [They] wondered how she kept it up year upon flatbacking year.
2006		Strip Club List 🌐 What happend to Nina, all kinds of rumors, she’s out flatbacking, she’s in jail again, she had to quit dancing to keep her kid.