A juror who was detained after he pretended to be sick so that he could go to a West End musical has said it was a "very stupid thing to do".
Matthew Banks, 19, from Staffordshire, was sentenced to 14 days in a young offenders institution after a judge found him to be in contempt of court.
He went to see Chicago in London despite telling court staff he was ill.
After being freed on Friday five days into the sentence, the student said: "I thought I would just get a fine."
The trial at Manchester Crown Court was halted for a day as other jurors were sent home because of Banks' absence.
Speaking to BBC Radio 5 live's Victoria Derbyshire, Banks, from Rugeley, said: "It was a very stupid thing to do - I genuinely did not believe I would put off the trial.
"I had already served two weeks and I was on my last day of jury service."
Banks, who is studying French at Manchester University, said he had been given a ticket for the musical as a Christmas present, adding: "There was a lot of people I didn't want to let down."
The student went to watch the musical with his mother Debbie Ennis, 49, who had no idea he had skipped jury service for the assault case trial.
He added: "Many of my fellow jurors had spoken about a case they had been on where the juror had had to leave and it carried on with 11 so I thought that by calling in sick it would carry on without me.
"I didn't think it would cause such a disturbance as it did.
"I didn't enjoy the day, especially when I heard that the case had to be postponed."
Banks' lie was uncovered when an employee from the court phoned his home and was told by his partner that he was in London.
He was in a coffee shop in London with his mother when he received a call from the court.
Banks said he had no idea he would end up in custody.
'Flexing his muscles'
"When I was told to go to court I was just told that the judge might want to speak to me before the case restarted, then I was taken straight up to the dock and remanded in custody," he added.
"I spoke to a barrister who said he was probably just flexing his legal muscles and I should get a fine."
Sentencing him on Monday, Judge Martin Rudland said lying to court officials for such a frivolous reason was a serious offence.
A Ministry of Justice spokesperson said offenders serving a 14-day sentence were released after seven days and this could be brought forward if the release date fell on a weekend or bank holiday.
The week-long trial, which Banks had been sitting on, later continued in his absence with the remaining 11 jurors reaching a verdict, Judicial Communications Office officials said.
Mrs Ennis said the family was now looking at appealing against his conviction as it could damage her son's future job prospects.