The Hour of Opposition was a time that came once in a Romulan year when Remus catches up with Romulus's orbit and the two worlds reach the point where they are closest where they would be more than a million kilometers apart.
Traditionally, it was a time of celebration on both worlds, though more so on Romulus itself, where schools and businesses close while families travel to be together to share meals. Game birds are consumed to instill the spirit of the Imperial raptor which has brought the worlds together again, as they were in the beginning. (TOS novel: Captain's Blood)