As we know, the ancients were extremely promiscuous in their paintings and other works of art. There are many examples of Roman frescoes with visible phallus or inscriptions referring to sexual matters. As it turns out, the Romans also liked to use sexual comparisons in colloquial speech.
For example, gladius – being a Roman sword – in the colloquial language of the Romans meant the male genitals. For comparison, vagina is otherwise “sword scabbard”.