The entire graduating class at an exclusive Australian boys school has been suspended over "unacceptable" end-of-term antics.
Up to 100 of 250 Year 12 students at Xavier College, Melbourne, allegedly took part in the "muck-up day" trouble.
They ran through the school wearing only their school ties as G-strings, and set off fireworks at a nearby railway station, media reports say.
Classes have been cancelled until Wednesday, the scheduled final day.
The trouble began at lunchtime on Monday - "muck-up day", an unofficial tradition of graduating students taking part in end-of-term pranks and other activities.
Police said they received numerous complaints relating to up to 100 students running rampage in the neighbourhood.
They were said to have harassed drivers and disrupted traffic, and there are also allegations that vehicles were damaged.
The students - aged 17 and 18 - are also accused of running semi-naked through the school grounds and setting off fireworks at the nearby Balaclava railway station.
One student was admitted to hospital with multiple fractures in his leg after a playground game reportedly got out of hand.
One neighbourhood resident wrote to The Age newspaper alleging the students were drunk and badly behaved.
"Their behaviour was disgraceful," the man said.
"They were blind drunk and some of them could barely stand. My kids have been through muck-up day, but I've never seen anything like that."
In response the school has cancelled all classes until Wednesday, which would have been the final day of teaching.
Exams are due to begin at the end of the month for the Year 12 students, said to pay A$16,000 (US$11,000; £6,500) a year in fees to attend the Roman Catholic school.
In a statement, the school said the boys had "contravened the boundaries of sensible behaviour" while playing a game, and that the "unacceptable" conduct had forced it to cancel remaining classes.
It did not refer to the trouble off-campus, but police have threatened criminal charges against the pupils involved.