23

Unlucky number for Tarvuists, after Tarvu lost his first mayoral campaign to Gibb by 23 votes.

Also, 23 is the age at which Tarvu transformed into Barvu, and unleashed Barvuism into the world for a full year.

Tarvuists never celebrate their 23rd birthday, and instead hold a sort of 'negative' birthday party (known as a 'Birthdimentiharbinge'), in which the birthday boy/girl renounces Barvu, and then gives presents to their loved ones and friends, which are then destroyed.

The luckiest number in Tarvuism is 9, although 8 is also considered lucky.