“The meaning of WC that we all use but don’t know”

The top:
It says WC in large black letters, and below it are two symbols: one for a man and one for a woman. It means a toilet for everyone. The bottom, in the black rectangle:
It says in English:
“Most people still don’t know what the acronym ‘WC’ used in restrooms stands for.”

Translation: “Most people still don’t know what the acronym WC used in restrooms means.” And at the end: “See full story in the first comment.” What does WC mean? WC = Water Closet
In Arabic: “Waterroom” or “Toilet”