The Inbetweeners star appeared on This Morning today to discuss her new book Are We There Yet?, which explores her life's highs and lows, with Phillip Schofield and Holly Willoughby.
The hosts reflected on Atack's childhood growing up in a home of entertainers before asking about the bullying she suffered as a youngster. Atack then recalled an incident where a group of bullies targeted her by encouraging people to prank call her.
The 29-year-old explained: "They stuck a photo up of me. God, it's so weird talking about all this now because I haven't talked about it in such a long time but it still freaks me out.
“They put this poster up of my face around some of the villages and they put my number on it and said that everyone could prank call me.
"I think people think that's funny. I've never had that in me. I can't understand how anyone would want someone to feel that way but then I always looked at it like maybe some of these people, they didn't have a privileged upbringing."
Atack grew up as no stranger to showbiz with comedian mother Kate Robbins and a musician father, Keith Atack.
Meanwhile, she counts actor Amy Robbins as her aunt, entertainer Ted Robbins as an uncle and she's also a relative of Sir Paul McCartney through her grandmother, who was the Beatles' cousin.
Atack was a runner-up on last year's I'm A Celebrity...Get Me Out Of Here!, losing out on the jungle crown to Harry Redknapp.
However, she will be back on screens in connection with the programme when she returns to host its sister show Extra Camp in November.