According to Reference.com, the medical term for the extra skin found on the elbow is olecranon skin. However, the more commonly used word for this skin is weenis or weenus.
The word weenis or weenus is viewed as an odd name for the extra skin around the elbow. This slang is not a type of medical terminology and there are no origins known for these words. According to Better Medicine, a rash on this area of the elbow can be caused by a number of reasons. It may be an indication of something around the actual elbow area or suggest a type of systemic condition.