According to Robert Hazard:

I changed all the lyrics over the phone with her. Originally, it was from the guy’s point of view. We had to make a lot of gender changes. She took the first verse and second verse and switched them. Why, I have no idea. Melodically, it’s exactly the same.

She actually had the guts to say in interviews that she wrote part of it. We sent her a cease and desist order. She did come to me with one line. I used to say, ‘All my girls are going to walk in the sun.’ And her line was ‘I want to be the one to walk in the sun.’ The original version was a guy talking about his girlfriends. A gender switch is a common thing and no one takes credit for it.

Lauper told Yahoo! Music after hearing the demo,

I understood how I could sing from my point of view and make it a call to solidarity for women. In the 1980s, women were still struggling to be seen as equal to men. When the women’s movement really started in the ‘60s and '70s, I felt so empowered and it was thrilling to me. But in the 1980s, it seemed that a lot of the hard work by people like Betty Friedan and Gloria Steinem had been forgotten, and women were once again accepting the status quo. We had gotten far, but not far enough … My idea was to use [Eric Bazilian and Rob Hyman] and their reggae feel and this wonderful new sound of this electronic drum and use the wonderful new styles that came over from England from groups like The Clash and how they approached their guitars. It was kind of raw. And also Andy Summers, who I felt played in a completely different way than what we were listening to, way more blues-oriented. I just felt there was a way to incorporate everything and use a big voice, which I had.

Yes. “Girls Just Want to Have Fun” was certified platinum by the RIAA on April 17, 1989.