A 15-year-old girl only realised she had been the victim of a degrading sexual assault after mobile phone footage began circulating in her school playground.
Ryan Bibby, now 19, has been jailed for two-and-a-half years for the sickening attack.
A 15-year-old girl who stood accused of aiding Bibby was acquitted of sexual assault.
Manchester Crown Court was told that at least two other young people encouraged Bibby as he molested the drunk teenager while another young person filmed the attack.
Lisa Boocock, prosecuting, told Manchester Crown Court that the schoolgirl was partying with a number of other youngsters at a flat occupied by a friend of Bibby's.
Miss Boocock said that the girl consumed a lot of alcohol and woke the next day with no memory of the previous night's events beyond dancing with Bibby and kissing him on the cheek.
The Manchester Evening News reports that is was three months later when the girl was told by a friend that obscene mobile phone footage of her was being shown around their school.
The distressing footage showed her face-down on a bed while Bibby assaulted her in front of two other teenagers. Her pleas for him to stop were ignored.
After seeing the video, the teenager and her family informed the police and Bibby was arrested.
Miss Boocock told the court that the assault had a lasting impact on the girl.
"She struggles to sleep at night, worrying about things. She doesn't feel she can trust anyone any more," she said. "She feels afraid in case anyone comes up to her about what they have seen on the video, because she doesn't know who has seen it. It's affected her school work."
The court was told that Bibby claimed he had no memory of the assault, but accepted he must be guilty after seeing the footage.
Sentencing Bibby, judge Michael Henshell told him he had subjected the schoolgirl to a 'most undignified assault'.
"There were others present who also played a part in what went on. Somebody filmed it, people were encouraging your behaviour.
"One of the more disgusting parts of it is you playing to the gallery, trying to entertain them with your activity," he said.
"The victim now feels ashamed to show her face outside – she has to live with the knowledge that anyone she might bump into will have seen her being used in that way."