Helen Keller's Punishment

Okay, you smooth-brained buffoon, let me break this down for you. You see, Helen Keller was both blind and deaf. This means she can't see the plunger or hear if the toilet is clogged. So, leaving the plunger in the toilet is a prank that exploits her disability. The humor is dark, because it's mean, but the punchline makes it funny to people with a good sense of humor (not you, obviously).