Term denoting the marking a Tarvuist's 23rd birthday.

In Tarvuism, the number '23' is considered unlucky, and so the day of one's 23rd birthday is considered a sad time.

On turning 23, Tarvuists must renounce Barvu and Barvuism publicly in front of their friends and family. This involves a special anti-Barvuist dance and some very loud and aggressive chanting. Since the late 1960's, it has become fashionable, even, to place Birthdimentiharbinge messages in local and national newsapers (in the classified sections), in which the Binibinbin (the term given to the person who is holding their Birthdimentiharbinge) writes a message of rejection, addressed directly to Barvu. These typically begin, 'Dear Disgusting Barvu…'.

At a Birthdimentiharbinge gathering, the Binibinbin does not receive birthday presents, rather they themselves give presesnts to their guests, who unwrap and then destroy the gifts in front of the Binibinbin. It is considered very bad luck to keep a present given by a Binibinbin. Pieces of card with the word 'Barvu' written upon them are also burnt, with the ashes flushed down toilets or poured down drains. Furthermore, items of food and drink, that the Binibinbin are known to dislike, are eaten. Traditionally, this has come to mean marzipan, anchoives and salted tea.

This goes on until precisely 23:01 (i.e 11:01 pm), when the Binibinbin may consider themselves free of the constraints of their Birthdimentiharbinge, and is allowed - for the next 59 minutes - to do anything they want (normally this involves getting drunk, and doing some heavy petting!).

Above: Birthdimentiharbinge ceremony for Lord Otsley, London, 1905. Otsley recieved over 5000 gifts, which took him over 2 weeks to destroy, as amongst his presents were 6 golden stage coaches, 10 horses, and 300 finches.