A bird did this amazing crap on my window the other day. I wish I had of seen it occur because it seems to defy physics. This is a vertical surface with no space above it where a bird could perch which leads me to believe the bird was in flight. Carrying a remarkably large load, the bird must have flown towards the window. At the very last second before slamming into the building, the bird must have squirted its load while making a sharp turn and letting the inertia carry the crap onwards. An impressive effort really.