I replied elsewhere on this topic about the same thing. They were indeed called "stiffy/stiffies" because they were more stiff than a floppy. Only when I grew

I replied elsewhere on this topic about the same thing. They were indeed called "stiffy/stiffies" because they were more stiff than a floppy. Only when I grew up and my juvenile sense of humour matured did I appreciate the hilarity of this naming convention.