The text plays on the double meaning of the word 'bait.' In one sense, 'bait' refers to food used to lure fish or other animals, suggesting that sushi is just raw fish used for this purpose. In another sense, it humorously implies that what is considered a delicacy (sushi) is seen by others as something less sophisticated or appealing.
Sushi : known to the rest of the world as ' Bait '