Michelle Trachtenberg Felt Uncomfortable Slapping Zac Efron

'Seventeen Again' is about a middle aged man (Matthew Perry) who finds himself changed into the body of a 17 year old (Zac Efron). Michelle Trachtenberg, who plays his daughter, told Hollywood.com, 'I call him dad. [I say things like], Good morning, dad.'

One scene involved Michelle slapping Zac really hard, and admitted she wasn’t comfortable with it:

“I felt really bad because the other night I had to slap Zac and that was really hard for me to do. There were like three takes and he was such a trooper. His face was burning red and I was like, ‘I’m sorry!’ He was like, ‘Just do it. Come on!’ He was so funny."