A father who suspected a bride-to-be of having sex with his 15-year-old son made her take a Jeremy Kyle Show-style lie detector test to prove her innocence.
The dad confronted Michelle Kay, 40, and demanded she take the test he had seen on TV.
Kay, from Colne, Lancashire, denied seducing the youngster but failed the test and police were called in to arrest her.
At Burnley Crown Court, Kay admitted four charges of sexual activity with a child plus another offence of causing or inciting a child to engage in sexual activity.
The mother of two began her seven-month fling with the youngster while babysitting for him in February 2011. The pair were watching a film on TV at a house when they began kissing and having sex.
"The teenager had touched the defendant, expecting to be stopped, but she let him carry on," said Katherine Johnson, prosecuting. "The two of them kissed and matters progressed."
They also had sex while a teenage friend was in the same room playing on a Playstation. Later, the boy went to see Kay to comfort her after she rowed with her fiance, who was away working. Kay had agreed the boy could stay over, but they ended up in bed together after he comforted her when she became upset.
Miss Johnson said: "He heard her crying and they cuddled. This led to the two of them having sexual intercourse."
The allegations came to light after the boy, now 16, told a friend, who then told his mother. The boy's dad was informed and confronted Kay.
Defence lawyer James Heyworth said: "The boy's dad reached somebody who had been on the Jeremy Kyle show. Such a test was taken and she failed.
"The lion's share of sexual offences heard before these courts usually tend to involve male defendants.
"This complainant was a sexually experienced teenager. She should have just walked away but she just allowed it to continue. It is not the same as an old teacher showing a young man the ways of the world.
"She is ashamed, embarrassed and shocked about what had gone on. For her there is a very real and genuine sadness for what's gone on and a real genuine fear of what the future holds for her."
Passing sentence, Judge Jonathan Gibson told Kay: "You had sexual relations with a boy who was aged 15 when it began and 16 when it ended.
"This is a serious case and activity of this kind is disapproved of generally by society. I have decided that a custodial sentence is inevitable."
Kay was also ordered to sign the Sex Offenders register for 10 years and she was banned from working with children for five years.