Meaning

There's a bit in Bo Burnahm's "what." Comedy special where he says something to the effect of "Sometimes I don't feel real, so I say words in an order that have never been said before so I can feel like I'm done something never done before, and therefore human and not some meaningless speck in the universe." He follows this setup with the punchline "Have you seen the Amish website?" and "I'm your dad and I liked your comedy special." Great stuff. But, it has gotten me thinking. How do I know I'm not some brain in a jar in a lab somewhere being sent random signals? What makes me different from the other 7,999,999,999 people out there?