Oxford Colleges are (or were) out of bounds to police and suchlike officials, unless invited in. A "bump supper" is held when the college boat has had particular success that year and moved up the league table on every day of the competition (Eights or Torpids). My college (Corpus Christi, Oxford) had a bump supper in 1967 (I think). We can leave aside the bun fight in the Hall over dinner; the real celebration started afterwards with the ceremonial burning of an eight (a boat - we got an old unwanted one from a nearby school) in the centre of the main quad. It burned very well - so well, in fact, that the authorities in the next college summoned the fire brigade, afraid that the sixteenth-century buildings really were aflame! (or maybe just out of spite).
The main gates were closed, to keep students from other colleges out. When the bell was rung, the porter went to see who was there, and opened the small postern gate; he was pushed aside by a fireman pulling a hose, already dripping water. The porter then slammed the gate, making a hole in the hose; the dean (an old rowing blue himself) appeared and ordered the firemen off the premises; some students let off fire extinguishers over the firemen from overlooking windows (they were severely punished, of course, for putting the buildings in jeopardy by depleting their protection); and one student jumped into the fire engine and drove it off.
Well, when the police tried to charge the student with driving a fire engine without a licence, it turned out that he was in fact a volunteer fireman in Ceylon (as it still was), and his licence from there was valid in the UK! So they charged him with: "taking and driving a fire engine without the permission of the mayor and aldermen of the city of Oxford", and he got a modest fine.
Meanwhile, another student shinned up the
sundial in the centre of the quad (there's a
copy of it at Princeton), and delivered a karate chop to the statue of a
pelican on top, whose head fell off. Apparently this happens about every 75 years or so; he had to pay for its replacement, which was not cheap.
Just another night keeping traditions warm.