What does a shark smoke? Sea-weed.
How do whales breathe underwater? They take a deep meth.
Okay, listen up, smoothbrain. The "joke" is playing on words. Sharks supposedly smoke "sea-weed" instead of weed (get it, cuz they live in the sea? I know it's hard). And whales are taking a "deep meth" instead of a deep breath. You probably think whales are fish, huh?