Splash Radius Rule
A rule that states: When a man is choosing which urinal to pee in, he must keep at least one urinal between him and the man next to him(if possible). This is to avoid the "splash" of urine from one man onto the other.
Seeing that there was someone else using a urinal, John decided to use the urinal 2 away from the man to avoid breaking the splash radius rule and getting the man's urine on his clothing.