In case you haven't heard ... the project is called "Skank Robbers" -- a wacky action comedy about two lady bank robbers ... with Lawrence's Sheneneh character from "Martin," Foxx's Wanda from "In Living Color," and according to reports ... Tyler Perry's Madea ... from every bad movie you've seen. The project is reportedly in development.

Enter Shamont Lyle Sapp -- who, coincidentally, says he's serving time in Oklahoma for 10 bank robberies -- he's filed a lawsuit, claiming he gave Foxx and Perry the idea for the project ... and they cut him out of the action.

According to the docs, Shamont had the idea to unite the three characters in one film -- but his version wasn't a comedy about bank robbers ... it was a drama about a mental hospital.

The lawsuit encapsulates Sapp's idea -- "A male white mental patient takes Madea hostage ... He deals with phone calls from the negotiators, as Madea actually pleads for her life in a very sad tear-jerking way ... Her pleas are to be very sad. No jokes at all."

Sounds like a blast. Shamont is also suing Fox Broadcasting and producer David Zuckerman for a total of $4 million in damages. Calls to Foxx and Perry's camps were not returned.