Monk Walk
The Monk Walk is a tradition from Lancaster. Starting from the Alcove, a huge number of CTYers carrying trays walk through the Dining Hall. As they walk they repeat the Monk's Chant from Monty Python and the Holy Grail and bonk themselves in the head with their tray, as such:
Pies Iesu Domine,
[bonk]
Dona Eis Requiem
[bonk]
The CTYers chant as they circle the cafeteria. They usually go around at least three times, causing many headaches but also much rejoicing.
Traditionally, this was done at the Last Lunch (Last Friday). However, at least at 06.2, to do so would make a third of the camp late to class, or make a third miss it altogether (in 05.2, the Monk Walk had to be done twice at lunch). As such, it was done at the Second-to-Last Supper (Third Wednesday), allowing everyone a chance to join in.