The Rainbowger is the same as the original Krabby Patty, except that the patty is rainbow colored.
Role in short
SpongeBob makes the Rainbowger and attempts to serve it to the customers, commenting it "will bring the whole world together." However, Plankton arrives and takes away the patty's color with his color nullifier. This makes it jam and start shooting random colors, coloring people random colors.
Its name is a portmanteau of the words "rainbow" and "burger."
It is one of the few Krabby Patty variations not to have the word "patty" in its name.