High jinks are something of a tradition for students celebrating the end of their final university exams in June.
Bring a bottle - but don't open it, rules say
But some at Oxford University have been taking it too far, prompting a lot of complaints from dons and the public.
So now a code of conduct is being drawn up by university and student representatives and the police and council.
Anyone throwing flour or spraying champagne around would face an instant fine, of up to £70 - and could be arrested for a breach of the peace.
A spokeswoman for the university said too many finals celebrations had been getting out of hand.
"I think the feeling was over the years that people might have got the impression that this was acceptable," she said.
"We're all for students celebrating and having a good time but we also want to make sure that they still consider the other people living in the city."
She stressed: "We don't want to stop students having fun, because they have worked incredibly hard."
The code will forbid throwing things such as champagne, flour, eggs, shaving foam or "silly string" and anything other than glitter or confetti.
Taking food or fluids to celebrations with the intention of using them in this way would also be an offence.
There would be spot fines of between £30 and £70. If police considered the behaviour amounted to a breach of the peace, they could arrest those responsible.
The code would apply within a six-mile radius of the heart of the city.
The Oxford University Student Union welfare officer, Rosie Buckland, said there had been general problems with noise and the mess of thrown flour or discarded bottles.
Her main concern was that people could be hurt by things being thrown around.
Also some Muslim students had been upset by being sprayed with alcohol.
"There have been a number of complaints over the past few years and student numbers have increased and celebrations have got more out of hand," she said.
Matters had come to a head in 2003 following the disbanding of the university's own, archaic police force.
Superintendent Keith Ringsell, of Thames Valley Police, said they would get involved only in "very extreme" circumstances.
He said: "We have never demanded a complete ban on the celebrations.
"But we do ask that they consider the views of those living in and around the Merton Street area, who may not appreciate waking up to buckets of pig's offal on the street or being pelted with flour and silly string on their way to work."
Regulations about student conduct are issued and reviewed annually by a university committee, half of whose members are student representatives, and are enforced by officers known as proctors.
They already prohibit "any activity likely to cause injury or to impair safety" and "violent, indecent, disorderly, threatening, or offensive behaviour or language".
In that sense the code contains nothing new, the university spokeswoman said - but there had been a feeling among some residents and university staff that the rules should be used to ban any form of street party.
So the code was "a much better compromise".
Its stated aim is to allow students "to celebrate, but to minimise both the danger caused when crowds gather and the disturbance to local residents, examination candidates, drivers and passers-by."
It is expected to be agreed by the university authorities and students' union next week, and will be e-mailed to all students.