In the film Edit
In the movie, when Forrest enters the Army bus, Bubba lets Forrest sit by him, and asks him if he's ever been on a shrimping boat, to which Forrest says "No". Bubba says he's been shrimping his whole life, and that his mother also is in the business, cooking shrimp, and her mother (Bubba's grandmother), and her mother (Bubba's great-grandmother). Bubba wants to go into the shrimping business after his time in the Army.
During their basic training, Bubba talks about all the different things and dishes with shrimp. Eventually the two are sent to Vietnam, where they get caught in a rain that continues for four months. One rainy evening, Bubba asks Forrest to come into the shrimping business with him as his First Mate and split profits. Forrest agrees to this.
The next day the rain stops and the soldiers are immediately ambushed by the Vietnamese. Lt. Dan orders the soldiers to pull back and Bubba tells Forrest to run. Forrest does, but soon is all by himself and rushes back to find Bubba. After finding and rescuing Dallas, Tex, Cleveland, and Lt. Dan, Forrest finds Bubba laying down in the grass, having been shot in the chest to which he picks Bubba up and takes him to the river where Lt. Dan and the others are. Bubba then asks Forrest why it all had to happen and also says that he wants to go home, dying shortly afterward.
While Forrest is in special assignment, he tells a crippled Lt. Dan how he plans to fulfill his promise to Bubba and go into the shrimping business, to which Lt. Dan sarcastically replies that he himself will be Forrest's first mate. After Forrest's discharge, he does fulfills his promise to go into the shrimping business, and Lt. Dan does become Forrest's first mate. After a bout of little success and a hurricane which wiped out all the competition, Forrest ant Lt. Dan become very successful. Forrest also gives Bubba's share of the profits to Mrs. Blue, making her faint, and allowing her to retire.