In honor of Farrah Fawcett, let's revisit one of the major urban legends of the late 1970s: that the curls of Fawcett's hair, in her famous red-bathing-suit poster, spell out the word "SEX."
This legend arose to explain the incredible popularity of the poster, which sold over 12 million copies (by some accounts). It was always a bit of a mystery why that image in particular became such a focus of popular fixation. After all, there were plenty of other posters of scantily clad attractive young women. The subliminal seduction theory offered a seemingly plausible explanation. The poster was so popular, according to this theory, because the brains of young men were subconsciously perceiving the word "SEX" in her hair, and this triggered desire for the poster.
The word "SEX" is supposed to begin with the curls on her right shoulder that form an S. I can see the S, but I can't see an E-X.
Anyway, I don't think one needs to invoke subliminal seduction to explain the popularity of the poster. The combination of the smile and the nipples makes it an eye-catching image. And once it started to become popular, then the dynamics of group psychology kicked in, turning it into a fad.
Thanks to Joel B1, I think I've now identified where the "EX" is supposed to be. For the benefit of those still unable to see it, I've highlighted the entire word in the relevant section of the image.