Australian Defence Force recruits were forced to rape each other in horrific initiation ceremonies designed to "break in and humiliate new entrants," a commission investigating sex abuse heard yesterday. 

Recruits testifying at a Royal Commission into Institutional Responses to Child Sexual Abuse spoke of abuse so systematic that many practices had been given nicknames. 

A 'royal flush' involved recruits having their head flushed in a toilet that had been used; 'nuggeting' was the practice of smearing recruits' genitals will boot polish using a hard brush. 

One former navy recruit testified that he was often "snatched in the middle of the night and dragged to a sports oval," where he was raped and forced to perform sexual acts on other recruits. 

He told the commission that the advice he received from his superiors was to "suck it up." 

Abuse was not always sexual: one former recruit said that they had been forced to run down a corridor while being hit with sacks filled with boots, irons and other heavy items. 

"I still feel a lot of guilt and shame about the abuse," another man testified said. "I have suffered depression."

The hearings focused on alleged abuse at a naval training center in Western Australia and an army apprentice school in Victoria during the 1960s, 70s and 80s, as well as also among Australian Defense Force cadets since 2000.

The inquiry is part of a long-running investigation into sexual abuse in the Australian military.

Abuse first came into the public spotlight in 2004, when an appeals tribunal found that a military facility had fostered a culture of "bullying, harassment, intimidation, bastardisation, victimisation and violence." 

Officers in charge, the tribunal judgment had found, "effectively condoned" the abuse.