Mary Dilley, 19, and her friend, Brandon Wester, 19, both pleaded guilty to defeating the ends of justice in the Durban Magistrate's Court on Monday.
In her plea read into the record by her attorney, Dilley said she and Wester had hatched the fake kidnapping plan on 16 September.
"Brandon helped me tie myself up and he began taking pictures of me, which we sent to my best friend via BBM [blackberry messenger]," she said.
"[The best friend] then sent the pictures to my mother, together with a recorded message, which was done by Brandon and which said he had found the phone at the beach on the bench, covered in blood."
She said the next morning, they were arrested at Wester's house.
Wester, in his written guilty plea, said Dilley told him she wanted to "scare" her parents.
Both said they knew it was wrong and had no defence for their actions.
Magistrate Lily Mpongose sentenced them to a fine of R3 000 or six months in jail, wholly suspended for five years on condition that they not commit the same offence again.