Wenis has achieved the status of
a dictionary word and can be found in the online Merriam Webster
dictionary. Even Wikipedia is reserving the word for inclusion. It
refers to the skin on the outside of the elbow. The excess skin
allows your elbow to move and flex. Medically speaking, it
is called the olecranal skin.
The word has long been used as slang, because it sounds like
the male appendage. Sample usage, "I fell and scraped my
wenis."