Poop Burgers
Or:
Soylent Brown*

See, if we eat nothing but poop and soy milk,and cover most of the globe with high-rise communes in which we live five to a room, we can cram, oh, hell, 20 billion people or so onto this planet. Surely that is not too high a price to pay for continued economic growth and...uh...whatever else it is that unbridled population growth is supposed to get us...  We were going to eat dirt, but all the topsoil washed away...  So poop it is!



( *Link and witty phraseology via Metafilter.)