It was definitely Tiffany, she also released a version of The Beatles I Saw Her Standing There, when her 'music career' went tits up she resorted to getting her tits out for Playboy etc.
Tifanny redid the song in 1985, but here is an interesting twist... A group that called themselves Rubinoos re-did the song in 1977. There is a (more) rock version of the song came out in between Rubinoos and Tiffany. If you know who it was I ask that you share the wealth, cause I sure can't find it...