A teenager allegedly lured a former schoolmate to a suburban Melbourne car park, taking her hostage and tasering her over a social media insult.

Yasemin Ercan, 19, and her friend Ehab Sayah, 20, have agreed to plead guilty to offences including falsely imprisoning the 18-year-old over unspecified derogatory remarks made about Ercan on Instagram.

The alleged victim had agreed to meet Ercan, her former classmate, after a heated text message argument but was taken hostage after arriving at the car park of Braybrook Shopping Centre on August 13 last year.

Ercan and Sayah entered the woman's car, with Sayah holding a stun gun to the victim's torso while forcing her to drive and deleting her text messages, court documents showed.

After making the woman stop at a nearby reserve, it's alleged Sayah tasered her twice on the thigh, while Ercan spat in her face and slapped her.

The 18-year-old was then forced to call Ercan's friend to apologise for the Instagram comments, and say sorry to two more friends who got out of a BMW parked nearby.

"This never happened. You don't know me anymore," Ercan allegedly told the victim before she was allowed to leave.

"Don't put my name in your mouth. If you do, I know where you live."

A teenager allegedly took a former classmate hostage over a social media insult. Source: Getty More

After Ercan was arrested, police found text messages telling friends she would "smash the f*** out of" the victim, it's alleged.

"I'll pop her huge fake lips and ugly face," one of the messages allegedly read

The night before the alleged attack, Ercan also sent Sayah pictures of a white bag and black balaclava.

"A bag to tie on her head," she wrote.

"A mask for me.

"HAHA."

The duo were initially each charged with six offences, including deprivation of liberty and stealing a car.

These were dropped when the accused said they would plead guilty to false imprisonment in Melbourne Magistrates Court on Friday.

Ercan also indicated she would plead guilty to unlawful assault, and Sayah to intentionally causing injury.

Sayah has a criminal history which includes dealing with the suspected proceeds of crime and breaching a community corrections order.

Magistrate Denise Livingstone refused an application that his bail be varied to allow social media access.

"These people can't manage social media at all," she said.

"Realistically, it's all about kids getting on the (social) media, whipping up a frenzy ... it screams unacceptable risk."

Sayah and Ercan, who is also on bail, are expected to appear in Broadmeadows Magistrates Court for a plea hearing on September 13.

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