Bantha fodder (in Huttese, it's "bantha poodoo") was a derogatory term used to describe someone considered utterly worthless, fit only to be eaten by a bantha. It literally meant food intended for banthas, known for its foul odor and ability to attract stink-flies. The expression also served as a substitute for saying something was nonsense, for example, "There's enough bantha poodoo coming out of you to fill this entire lake." Calling someone a "sack of bantha fodder" implied they were a contemptible individual.
Back in 40 BBY, Rael Averross was explaining to Qui-Gon Jinn that he had tried reaching out to his former teacher, Count Dooku, who was on the planet Serenno, but he never got a response. When Jinn asked about it, Averross just shrugged it off, saying Dooku had become a ruler and was probably too busy dealing with "courtiers, bureaucracy, and all that bantha poodoo" that Averross had been dealing with for the past eight years on Pijal.
While playing cards on the moon of Dawk with the Devaronian criminal Coir Cion, Devi overheard Cion bragging about how he'd be a free man soon. He claimed that once he got his pardon, he'd leave his criminal life behind and go straight, no more running from the law. But Devi didn't think Cion had a chance of getting a pardon, dismissing it as "bantha poodoo."
When she was on Asusto, Jedi Master Lene Kostana noticed that the whole planet was consumed by the dark side of the Force, pointing out that trash was drawn to the planet "like stink-flies to bantha fodder."
During 32 BBY, Sebulba, who was a Dug, and Anakin Skywalker, another podracer pilot, were in a heated rivalry. Right before the Boonta Eve Classic was about to begin, the Dug couldn't resist one last jab at the young Skywalker, and they traded insults in Huttese. The young boy insulted Sebulba by calling him a "sleemo," and Sebulba shot back by calling Skywalker "bantha poodoo."
In Theed on Naboo, an unnamed Gungan child on the street was scared by Asajj Ventress, who threatened the young Gungan to "watch it, or you'll be bantha fodder."
In 2 BBY, the Spectres teamed up with the pirate Hondo Ohnaka and the crime lord Azmorigan for a mission to loot an Imperial cargo ship. When Azmorigan stepped onto the rebels' ship Ghost, the Spectres gave him a chilly welcome, especially Hera Syndulla, who remembered him as the "sack of bantha fodder" who had tried to buy her from "that sleemo" Lando Calrissian to make her his servant. Azmorigan retorted that she was the feisty one who had hit him with a tray and insisted that he still technically "owned" her.
During the hunt for Vader in 1 BBY, Dengar got more and more annoyed when he didn't get a response from Urrr'k, yelling, "I know you can hear me, you bantha poodoo."
In 0 BBY, Greedo watched as C-3PO and R2-D2 went with Luke Skywalker into the Mos Eisley cantina, where Wuher warned that the droids had to stay outside. Greedo thought about how foolish Skywalker was, figuring he'd be lucky to finish a drink in the cantina or even make it through another year, calling him "untried bantha fodder."
Three years later, Zev Senesca was one of the rebels stationed at Echo Base on the ice-covered planet of Hoth. Senesca noticed that some of the Rebels were trying to find comfort in their surroundings on Hoth by praising the natural beauty of the area, pointing out how amazing the vast ice plains and glaciers were. But he thought those sentiments were "a load of bantha fodder" and would have traded all the natural wonders in the galaxy for a toilet that didn't freeze your backside while you were sitting on it.
In 4 ABY, after being captured by the ruthless gangster Jabba the Hutt, Han Solo was brought before Jabba to be judged. Solo tried to beg for his life, but Jabba didn't care. He said that Solo might have been a good smuggler in the past, but now he was just "bantha poodoo."
A common misunderstanding is that "poodoo" is bantha excrement. Despite referring to fodder, using "bantha poodoo" to mean nonsense is similar to the real-world term "bullshit." The phrase "sack of bantha fodder," used to describe a despicable person, is similar to the real-world term "dirtbag," and the vulgar slang phrase "piece of shit."