The reason why is that raccoons are very fiercely protective and female raccoons are very monogamous, meaning they will only mate with one male raccoon. Not only will they avoid other males, but they will go crazy and fight other males who get near them or their nest. So young men noticed this and figured that there was some special magic in the penis of raccoons that makes their females fall so deeply for one and only one. They would give the bone of the male raccoon penis to the woman they loved to let her know they loved her and also to keep her faithful.
It is also a very strong protection charm. There are many stories of people escaping near death situations after receiving a raccoon baculum.