Broke: Whales are fish because they look like other fish

Woke: Whales aren't fish because they're in the class Mammalia, not Pisces

Bespoke: Whales are fish because any monophyletic group that encompasses all the fishes must also include the clade Tetrapoda

Artichoke: Whales aren't fish because fishes are a paraphyletic group that includes the entire clade Vertebrata at the exclusion of the clade Tetrapoda.

Stick and Poke: Whales are fish because they've developed the same bodyplan and are in the same ecological niche as the pelagic fishes.