Toshio Takahara explains, in words and a diagram [click on it for an enlargement], the engineering process that (he believes) led to a celebrated Dutch invention:
The men’s restrooms were not so clean at Schiphol airport in Holland. “Many men weren’t aiming very well and were missing the target… The problem was solved by drawing a small fly on the walls of the urinals to attract the attention of the men using the restrooms. It turns out that when a man concentrates on a certain spot, he naturally also aims in that direction”
