Arron Jackson, 44, of Hospital Lane, St Peter Port, admitted a charge of sexual assault, having originally denied it.
The court heard he had done it intending to ‘frame’ a mate for the offence as a joke.
The court was told how the incident happened in Folies nightclub at about 1.30am.
Police officers outside were notified by doorstaff of an inappropriate contact with the club.
When they spoke to the female victim, she said the defendant had squeezed her bottom over her clothing without her consent at approximately 10.15pm.
She was in no doubt who had done it and said that Jackson had been looking at her as he walked away.
Prosecuting Advocate Jenny McVeigh said the woman had confronted the defendant about what he had done.
Jackson told police at the scene that he had grabbed a girl’s bottom as he was intending to frame his friend for it as a joke. He gave no comment responses to questions later in interview.
A date for trial had been set before he changed his plea to guilty.
The last matter on his record was from 2025 when a prison sentence of two months suspended for two year was imposed for an incident in which he resisted police officers in the due execution of their duties after being found drunk in a public place.
Defending, Advocate Chris Green said his client’s ‘misconceived prank’ had backfired on him and he wished to apologise to the complainant.
He had been going through a period of instability at the time due to medication and it was the complainant’s friend who confronted his client in the club, not the woman herself.
The probation officer had concluded that he had not done it to satisfy his own sexual desires.
Judge Gary Perry said the woman had spent eight months expecting that she would have to give evidence at trial.
The defendant had told the probation service that men used to slap women’s backsides as a way of flirting, which only made things worse.
That type of thing was only ever seen as flirting in the eyes of men, he said.
‘Women used to put up with it but fortunately we have got to the stage now where the impact that this type of offending can have on them is well known but not, it seems, by you,’ he told the defendant.
‘Women have been forced to change their habits and the way they dress because men like you treat them as objects.’
He said it was ‘appalling’ that Jackson had done this just to get a laugh and it was a blatant breach of the previously imposed court order.
Jackson was sent to prison for one month for the sexual assault. The previously-imposed suspended sentence of two months was activated in full, to run consecutively. He will be subject to notification requirements for two years.