Helen Keller's Tight Pants

Alright, you smooth-brained chucklehead, let's break this down. You see, Helen Keller was both blind and deaf. So, the joke plays on the idea that someone might try to "read her lips" - something that's obviously pointless because she can't hear. It's funny because it's absurd. The tight pants bit? Just a setup for that ridiculous punchline.