JT's penis size. Calculated to be approximately 9.7x10^834719^9203^3943209^241573^937348 inches. Which most scientist consider to be an understatement of the true number.

Briefly, "the realization that each random passerby is living a life as vivid and complex as your own." Originally from the Dictionary of Obscure Sorrows, which has a lot more beautiful neologism definitions like this you might enjoy.