The Raw Sewage burger looks similar to a Krabby Patty except it is darker in color. It also has dark green sauce on it that resembles raw sewage. The ingredients look much more decayed and the patty contains a strange odor.
Role in episode
SpongeBob thinks that Plankton stole the secret ingredient for the Krabby Patty until he finds out that the burger is not a real Krabby Patty and just a failed duplicate attempt. Plankton explains that he is going through every single ingredient there is to try and duplicate a Krabby Patty, and that he is on the R's and Raw Sewage is his latest attempt.
After SpongeBob and Patrick leave the Chum Bucket, Patrick is shown with bad breath coming out of his mouth, indicating that he ate the burger.