The leaf is a centuries-old plant organ, an extension and major part of a tree (also known as the Pear Tree and Magic Circle of Life ensemble). It is also an ancient phallic symbol, remarkable for the notoriety gained in the Middle Ages. It is now both a symbol of life, penises and good old horniness.
During the Middle Ages, purity was an important part of Christianity. Lust and horniness were big no-nos. Under the pretense of purity, the old-fashioned geezers would place fig leaves on the penis of certain "indecent" sculptures, leading to men, women and aliens alike to gaze dreamily at sculptures and wondering how big was the organ underneath the fig leaf, all the while "studying pieces of art". Adam and Eve also wore fig leaves after having eaten the fruit from the Tree of Knowledge, and it may have contributed to their remarkable ability to beget children.
Leaves are a great way to cover up tiny old man cocks and old stretchy vaginas cuz no one wants to see that shit. When using a leaf as a penis-cover-upper never use poison oak cuz unless you already got the herpes it will itch like a bitch.
The fig leaf was so often placed in front of the penises of classical sculptures that many females with overly protective mothers grew up believing that men were indeed equipped with leaves, leading to many surprised shrieks from closed bedroom doors after wedding nights. However, many people have misinterpreted those shrieks and disregarded them.
In modern times, any mention of "fig leaf" is sure to bring any mind down into the gutter, and sparking a long debate about censorship while the debaters are all secretly thinking about penises and will sometimes replace the word fig leaf with penis. However, you are likely to not notice this as when anyone is observing one of these debates, they will invariably be led to think about penises and not notice as the participants in the debate begin to talk about penises instead of fig leaves and censorship.