A 12-year-old girl was sexually assaulted after drinking with friends in a local park.
James Tough targeted the girl, who was nearly half his age, in the bathroom of a house in Arbroath.
A group of youngsters had been drinking at a local park but moved to a nearby house when they were moved on by police.
They were drinking a bottle of vodka which claimed to be 100% proof, the High Court in Edinburgh heard on Friday.
Tough, 23, met the group after going to the park to meet his cousin.
He took the young girl into a bathroom and sexually assaulted her on May 20 last year.
Tough of Charles Avenue, Arbroath, admitted indecent assault.
Defence advocate Ronnie Renucci said although Tough was 22 at the time of the offence he had a very low IQ.
The difference in maturity between him and the girl was not as great as their ages might suggest, the court heard.
The judge, Lord Uist, called for background reports and allowed Tough to remain on bail - ordering him not to be left alone with children.
Tough's name has also been added to the sex offenders register. He faces sentence in Glasgow next month.