It's like spam opposite day!
This is a replica of an actual 15th-century invention, created to do exactly what it sounds like. It's from the personal collection of Erwin Kompanje, a medical ethicist fascinated by forgotten medical discoveries.
Of course, while it flies in the face of everything you've learned via Maxim and unsolicited emails, there's a very good reason for the penis-shortener to exist. Frankly, sometimes over-endowment can be a hindrance. A painful hindrance. Kompanje first wrote about this in a research paper published in 2006 in the journal Archives of Sexual Behavior. If you understand Dutch, you can read more about the penis-shortener—and other forgotten medical advancements—in Kompanje's new book, titled, De Penisverkorter.