Rolf Harris told an 11-year-old girl he wanted to be the first person to give her "a tongue kiss", a jury has heard.
The woman, who cannot be named for legal reasons, told Southwark Crown Court that she met the artist at a family friend's home in Australia in 1969 while she was off sick from school.
She came downstairs in her pyjamas and saw Harris - a Sydenham resident in the 1960s and 1970s - who had been polishing a piece of wood, the court heard.
The woman said: "When I came down the stairs he asked me how old I was, and he said 'good, I want to be the first one to introduce you to a tongue kiss'.
"I just stood there, I didn't think anything. I just stood there, I froze."
It is claimed that Harris, 84, then walked up to the girl and kissed her, putting his tongue in her mouth.
She said he got her in a "gentle hug" but that she could not move and was scared.
"He put his tongue in my mouth and gave me a tongue kiss.
"It seemed like it lasted forever but it must have been very quick," the woman said.
She is not one of the alleged victims on the indictment because the allegation is said to have happened abroad before such matters could be prosecuted in the UK, but has been called as a supporting prosecution witness.
Harris, from Bray in Berkshire, is accused of 12 counts of indecent assault on four alleged victims between 1968 and 1986, all of which he denies.
The woman told the jury of six men and six women: "I was quite repulsed by it. Absolutely repulsed."
After the alleged abuse Harris stopped and showed her the wood he had been polishing, the court heard.
"He just stopped and then he just went and said 'have a look at what I've been doing'."
The court heard that she told "a couple of friends" about her claims, but was not taken seriously.
"They didn't believe me and so I said nothing."
She said that she had told each of her three husbands about the allegation, because it made her uncomfortable about being kissed in that way.
"It makes me feel very frazzled and scared and I almost have a panic attack," the woman said.
"I told them it's because it's a leftover from when I was a child and this happened to me."
The court heard that the woman was assaulted by her cousin when she was 17, but was forbidden from reporting it by her parents.
"I wanted to say something but my father wouldn't allow me to. He said it wouldn't be appropriate to say anything," she told the court. She said she had to "suck it up and get on with it".
Eventually her husband persuaded her to go to the police about the Harris claim, following media reports about the veteran entertainer.
In cross-examination, the woman said the incident with her cousin "triggered" the memory of the alleged Harris abuse.
"It triggered my memory to bring it up again," she said.
However the woman rejected a suggestion by Sonia Woodley QC, defending, that she had confused the incident with her cousin and the Harris claim.
In re-examination by prosecutor Sasha Wass QC, the woman said: "There's no possibility I can mix them up. The incidents are very separate incidents. The feelings that come from them are similar feelings, but the incidents that happened are separate incidents."
The court then heard from a second woman who broke down as she said she saw "the dark side" of Harris when he groped her as they danced.
Jurors were told that she was 16 or 17 and was working for a wine company at a party in New Zealand in 1970 when she met the entertainer.
She said that she and another member of staff had photographs taken with Harris and his friend, and he gave her his autograph.
The woman said: "I thought it was quite special, meeting somebody. He was a celebrity from television.
"I was quite honoured to see him coming through the door."
At first he was "very friendly and very relaxed", and was "being stupid" posing for the pictures, she said.
"He was being stupid. He was acting up for the camera in a way that he wanted to be noticed by the camera.
"He was very comfortable with himself, he was very confident, he was making everybody feel very relaxed. He was the public Rolf Harris, the entertainer. A very big act. Very 'look at me', laughing and joking.
"I thought he was exactly what he was on television. I thought he was friendly, I thought he was very friendly.
"When he signed the autograph I didn't expect him to put 'with my love'. I felt totally comfortable."
Harris then asked her to dance, slid his hand onto her bottom and put it between her legs, the court heard.
Breaking down, the woman said: "We were dancing and we had had a photo taken, he was talking to me and I felt relaxed, comfortable. In a flash, in a moment...I saw the dark side of a man who I thought could be trusted. I was in a public place, he slid his hand down my back against my bottom and then in a moment put his hand up my skirt and tried to put his hand in between my legs."