Priapus is a Greek god of fertility and male genitalia. He is a large, walking and talking penis. Because of this Zeus, king of the Greek Gods, will often use him to address people he wants to shock, such as other bickering gods.
The two Roman Gods, Cardea and Portunes are constantly arguing over which of them is more integral to the functioning of doors. Their arguing annoyed the other gods, including Zeus. Zeus asked Priapus to ask the two of them to quiet down. Thanks to Priapus' shocking visage, he only had to begin talking to them to shut them both up[Pan 1].