The man told a Sydney court he was invited to Jones' NSW Southern Highlands property multiple times before attending during one school holiday period.
The then-17-year-old said he was not accompanied by a parent and there was no one else in the house when he leaned in to give the former ruler of Sydney's airwaves a goodnight hug.
He said he froze when Jones kissed him with tongue, then recoiled and stepped away when the then-septuagenarian grabbed his bottom without consent.
The teenager told him "That's enough Alan" and turned to enter his bedroom, but noted the veteran broadcaster wore a grin that made him very uncomfortable.
"I went in (to the bathroom) with a loofah … and scrubbed my mouth as much as I could," he recalled.
"I felt violated and I felt gross."
Under cross-examination by Jones's barrister Gabrielle Bashir SC, the complainant vigorously upheld his recollection.
He repudiated suggestions Jones hadn't kissed him, stuck a tongue in his mouth, or touched his bottom.
When the barrister put it to him he and Jones hugged goodnight "and nothing else", the alleged victim told her: "That's not true, Ms Bashir".
He accused her of being selective and omitting key events by describing the interaction as him hugging Jones, going into his bedroom, and going to bed.
"Mr Jones has been nothing but kind and generous to you over the years, hasn't he?" Ms Bashir asked.
"Mr Jones has been generous to me over the years, Ms Bashir, but the word 'nothing' is not correct," the complainant responded.
He had written to the longtime shock jock about his family's financial and personal difficulties when he was 13 years old, and Jones had agreed to help.
The former Wallabies coach advocated on the family's behalf, liaised with his political contacts, and spent more than $100,000 on assisting with their issues over several years.
In their hundreds of emails over the years, the court was told Jones had reminded the teenager it was "very important that you're grateful" to those assisting his family.
The complainant told the court he had been terrified of jeopardising the support his family had been given by making a scene about the alleged indecent assault.
He admitted he lied to authorities about a separate assault allegation made years after the alleged incident at Fitzroy Falls.
The court was told the complainant had presented to hospital with injuries which he said had been inflicted by assailants the night before.
But he conceded he knew the injuries had actually occurred weeks earlier, telling the court he had manipulated them to align with his timeline.
"I suggest to you that you have a selective view of the truth," Ms Bashir charged.
"That's your opinion, Ms Bashir," he retorted.
The complainant concluded his testimony in the witness box days ago but parts of his evidence were covered by a non-publication order which was lifted on Thursday.
He was the last of five complainants to testify against Jones, who has pleaded not guilty to 21 charges of indecent assault and sexual touching without consent.
One of the charges of indecent assault relates to the 17-year-old.
Jones is accused of behaving inappropriately between 2003 and 2020 - when he retired from his highly influential broadcasting career after more than three decades.
The trial, which began in August, has been adjourned until Monday due to illness.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
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