"The reality is survivors take up to 16 yrs plus to disclose (if ever) about being raped or sexual abused."
Key was on air when he was asked to go in a cage and "pick up the soap" a clear reference to prison rape.
One of the DJs then said, "you've got a purdy little mouth, Prime Minister", a quote from the film Deliverance which is said to a character before two men rape him.
The video has attracted wide criticism.
On air, RNZ journalist Guyon Espiner called it a "distasteful prison rape joke", and political commentator Bryce Edwards said "I was a bit uncomfortable listening to that".
Commentator and NBR contributor, Matthew Hooton, said "the cage, soap and rape thing was a complete disgrace".
Barry Soper from Newstalk ZB wrote a column asking "does John Key go a step too far?" and said Key wouldn't have been aware of the rape reference.
Herald reporter Claire Trevett wrote "there's a fine line between his usual schtick and bad taste".
This year, Mrs Nicholas was made an officer of the New Zealand Order of Merit for services to the prevention of sexual violence.
Her fight for justice in 2004 sparked public protests and the creation of Operation Austin to investigate alleged sexual offending by former police assistant commissioner Clint Rickards and his ex-colleagues Brad Shipton and Bob Schollum.