Rolf Harris’s youngest alleged victim told jurors he was a “dirty old man” who assaulted her “out of nowhere”.
The woman said she was just seven or eight when the veteran entertainer molested her while signing autographs at a community centre.
She broke into tears as she told London’s Southwark Crown Court she wanted to scream out during the incident, which happened between 1968 and 1970.
The woman, now aged 52, recounted how, when she reached the front of the queue of autograph hunters, Harris touched her inappropriately at the centre in Portsmouth.
She said: “He was looking at me, smiling, and I was smiling, looking excited, and suddenly out of nowhere I felt his hand go down the back and up between my legs.”
Then Harris allegedly touched her again, “aggressively and forcefully”. She said: “It didn’t matter if it was going to hurt me or not. It felt very aggressive and I knew that it wasn’t an accident.
“There was a moment when I was out of my body and I just wanted to get away.”
She also described the moment she wanted to scream out “What are you doing?” but said she was unable to do so.
She said: “I didn’t know how to put it into words. He scared me because he was looking at me all the time.”
Breaking down, the woman told the court she “wasn’t the same child” afterwards.
When asked how long she had memories of it, she said: “Forever. I can hear a song or something from that era and go straight back. I can shut my eyes and go straight back.”
Harris, 84, denies 12 counts of indecent assault between 1968 and 1986. His alleged victims were aged between seven or eight and 19 when the offences are said to have taken place.
The court was also told the presenter and artist had groped a teenage girl after she saw him on all fours barking at a dog.
The woman said she was working as a waitress at a celebrity event in Cambridge when she was 13 or 14, and went outside when she and her colleagues heard the animal noises.
“He was on all fours and there was a terrier-type dog in front of him and they were barking at each other,” the woman said.
She said she felt “awestruck” at seeing the celebrity, whom she recognised “instantly” when she saw him at the It’s a Celebrity Knockout event in 1975 or 1976.
The woman, aged 52, told the jury Harris put his arm around her and moved his hand up and down her back, before squeezing her bottom.
She said: “I just stood there. I couldn’t believe what was going on, this famous person putting his arm around me.
“To start, it was a very nervous but a good feeling. However, his hand then moved and his hand went up and down my back and his hand went over my bottom and it was very firm.”
She told the court she had her back to the white marquee where the event was taking place, so the crowd could not see what was happening.
She said: “I was too young to really understand the term but it was basically like groping. It was very firm and he squeezed it a few times. I was just completely frozen. I knew it was wrong.”
She said she was “extremely embarrassed” and moved away as soon as Harris let go of her.
The alleged victim told the court that she has “a physical reaction” whenever she sees Harris on television or in a photograph.
The trial was adjourned until Monday.