While I do have mixed feelings about Ms. Magazine, as I'm sure many feminists do, there is some fantastic material from time to time.
Much like bell hook's Feminism is for Everybody is an excellent primer of feminism and explains why the feminist movement is still relevant today (and if you haven't read this book, feminist or not, you really should pick up a copy), this article from Ms. Magazine on sexual objectification is a good starting point for a conversation The piece is the first of four installations on sexual objectification, defining first what it is, then listing questions one can ask to help identify sexually objectifying material.
The article defines sexual objectification, writing, "If objectification is the process of representing or treating a person
like an object, then sexual objectification is the process of
representing or treating a person like a sex object, one that serves another’s sexual pleasure."
It's all very reminiscent of the Killing Us Softly series by Jean Kilbourne. If you're interested in advertising and objectification, much of her content is available on youtube.