I don’t get it. How is this related to star wars

'So long and thanks for all the fish!' is what the dolphins say in the Hitchhiker's Guide to the Galaxy, when they leave the Earth and fly off into space, shortly before the Earth's destruction to make way for a hyperspace bypass.

The Purrgil's in Star Wars are also a species of space-faring cetaceans and OP is making a meme linking the two.

What is a Purrgil? I don’t remember that from the prequels or the sequels