Some time ago, I was sitting on a bench outside the University of Maryland
mathematics building.  I turned to a sparrow beside me, and asked, ``What is the
deal with homotopy colimits?''  He looked me in the eyes, defecated on the
bench, and flew off.  In this moment, I understood the homotopy category
construction.

The sparrow's name?  Rodoljub Milenkovic.