How?

Clearing a blocked down pipe, I found the usual gunk and old leaves but the main blockage was this unopened bottle of Chocolate Milk Shake. With a sell by date of May 2013, I can only presume that the roofer who was slating the extension roof on the old house ( last March ) dropped it by accident, watched it disappear down the pipe and chose to let it be.
Perhaps I should return it.