Chum Bucket Supreme is simply a bucket of chum. The chum is served in smaller buckets that look similar to the bigger Chum Bucket that also read "FUM IS CHUM" on them. People eat the chum by putting it around their necks and eating it from the bucket.
One of the many customers who have eaten the Chum Bucket Supreme is Nat Peterson. Nat, so far, has eaten more chum than anybody.