Helen Keller walked into a bar...
And into a table, and into a chair.
Listen up, genius. Helen Keller was blind and deaf, so the joke is that she walked into a bunch of stuff because she couldn't see or hear where she was going. It's funny 'cause it's kinda mean, and you're probably the kinda person who trips over their own feet. You are now smarter than the guy who wrote this, so congrats?