What does the slogan "one small step forward, one big step for civilization" mean? Why does ipartment say that all boys know?

In other words, when urinating, you should move closer to the urinal to prevent urine from spilling on the ground. So the toilet will be clean and tasteless. Your small step is the embodiment and extension of civilization, which means that if you pay attention to civilization everywhere, everyone will be a big step forward in civilization.

This refers to boys! Of course, boys know.