Besides the "komedy k's" that was already mentioned, a kodiak bear is a very specific type of bear. More specificity is generally considered funny when you're describing a story in the form of a joke. Not only does it add tension by drawing out the conclusion, it implies the comedian has actually put some significant thought into the situation they're describing.

Not just a bear. Not a polar bear. Not a brown bear. A kodiak bear. The only thing funnier would be "a 8' tall, ill-tempered, honey-hating, monkey-fighting kodiak bear. Named Maurice."