I remember this one as a kid. It was in my Mum and Dad's record collection. I used to have a girlfriend who always used that title sentence as well. She often started by saying: "I'm telling you now..." and then it was followed by nagging or scolding about something.
It used to make me laugh, because I would think of Freddie and the Dreamers and start singing this song in response. She used to get more wound up.