A former student of The King's School in Sydney has told the abuse royal commission he was driven out of the school by relentless bullying that started after a boy ejaculated on his sleeping bag.
The now 19-year-old is the first from the prestigious private boys' school to testify at the inquiry, which is examining institutional responses to harmful sexual behaviours by students.
On Monday, the young man, referred to as CLC, described being a happy boarding student with plenty of friends until a cadet camp at the beginning of year 10 in 2013.
"During the night I woke up to hear laughing and one of the boys saying: 'Did you really do that? That's disgusting'," he told the commission.
"Initially I didn't know what happened but then I rolled over and saw that (a fellow student) had ejaculated on my sleeping bag.
"I immediately grabbed something to wipe it off."
CLC said the boy would have known that what he did was against school rules because they had been warned against "bush beating" - masturbating during camp.
The news of the incident spread fast through the school and students called him names to his face and via social media.
He said he had spoken to the head of the camp, housemaster Andrew Mansfield, and told him what happened but felt his concerns weren't adequately followed up.
Some boys claimed the student responsible had actually used condensed milk, he said.
"I do not know of anyone being punished by the school for what happened," CLC said.
CLC said the bullying continued until August, when he ran away from school and called his father in a distraught state.
CLC's father, called EAE, told the commission he secretly recorded a meeting with King's principal Timothy Hawkes where he said he was "disappointed" CLC had not reported the bullying earlier, allowing staff to help him.
"I took away from the meeting that the school was more interested in protecting its reputation than helping," EAE said.
CLC moved to St Ignatius College in 2014 and found it a kinder, bully-free environment, the commission heard.
Dr Hawkes, Mr Mansfield and deputy headmaster Dr Andrew Parry are yet to respond to CLC's and EAE's evidence at the commission.
Another elite Sydney school came under scrutiny at the commission on Monday, with Trinity Grammar principal Milton Cujes earlier admitting his school failed to properly investigate rape allegations.
Questioning centred around the first incident report made by a student on August 11, 2000 that some older students had tried to rape him.
The boy, referred to as CLB, wrote that the same group of boys were in the habit of sticking a 30cm wooden dildo they had made in wood-tech class up other students' bottoms.
Mr Cujes told the commission he trusted three other staff - his deputy, the boarding house master and the school counsellor - to handle the issue at the time.
"I didn't read (CLB's incident) report sir, that's not my recollection," Mr Cujes told counsel assisting David Lloyd.
CLB had also told the school counsellor, Katherine Lumsdaine, that the same boys had used a variety of pole-like objects to rape him more than 50 times, the commission heard.
The commission heard Ms Lumsaide was the only person who stressed the need for formal investigation.
Mr Cujes admitted he was part of the school's failure to conduct a proper investigation.
Mr Cujes, who is still headmaster of the prestigious inner-western Sydney school, denied the school tried to "hide things under the carpet".