Some traditions are ancient. Some were invented in 1926. It is considered vulgar to ask which.

New students enter the Great Hall beneath the portrait of Ethelred, swear to use SI units except where maritime or pub-based convention makes this socially impossible, and touch the Founder’s Spoon.
The Spoon is said to date from the tenth century. Metallurgical analysis dates it to approximately 1973. The College regards this discrepancy as “an unnecessarily literal reading of continuity”.
Undergraduates wear dark gowns. Engineers are permitted one oil stain of demonstrable provenance. Doctoral graduates may wear crimson provided they can explain uncertainty propagation without looking alarmed.

Held each Michaelmas since 1841. The Vice-Chancellor taps the principal boiler three times with a silver spanner while the choir sings Abide With Me at 50 Hz.
Contested against St Mildred’s Institute of Accountancy on the Upper Pidd. The river is 2.3 metres wide, so overtaking is considered unsporting and usually impossible.
Grace is delivered in Latin, dinner in three courses, and engineering opinions without invitation throughout.
At 4 p.m. on Founder's Day, a 40-litre copper kettle is brought into the quadrangle. Nobody remembers why, which is generally accepted as sufficient reason to continue.
Gerald is neither a Fellow nor an employee. He has nevertheless occupied the same workshop stool since 1998 and can obtain any connector you require.
Rung once to start an examination, twice to finish, and continuously if the Structural Engineering paper contains a sign error.