There are so much Folklore in Brazil!
Here one from Amazon:
This is the Boto, a river dolphin that lives in the rivers of the Amazon
Amazon Legend says the Boto can turn and go to parties in the region in the form of a handsome and strong man, dressed in white, tan and very fragrant, inviting the girls to dance and then he seduces them. But the dolphin never takes off his hat to hide his secret: a hole in the head where he breathes.
So every maiden was alerted by their mothers to take care of receiving flirtations of handsome boys at dances or parties. Behind them, could be the dolphin figure, a conqueror of hearts, which can impregnate them and abandon them.
The legend serves as a pretext to justify the girls pregnancy without marriage. "It was the boto", they say.
This is the Boto Legend being performed at Parintins' Festival