Potato Brain - WTF?

Out of context, this paragraph is only slightly more bizarre than it is in its proper place. From something called, "Snake Oil Men, Part 7":
We went to the hospital to get my daughter checked out. By this point we had a police escort, but nobody was buying my story about the Brotherhood. I was just a crazy old Nobel laureate with a swollen finger. But then something happened that lent credence to my story, something that would bring down a thousand year old fraternity of medical practitioners, newsmen, and fighter pilots. The X-rays of my daughter's head came back, and there, floating in intra-cranial jelly, was a brain the size of a potato.
My favorite part is the line about the swollen finger.