What is the most unusual thing you have found out about humans finding each other attractive?

Question: What is the most unusual thing you have found out about humans finding each other attractive?
- Keywords:
  attraction,
  attractive,
  exciting,
  fun,
  human,
  unusual
Asked by majaxx to Ed on 22 Jun 2011.
- Ed Morrison answered on 22 Jun 2011:
  
  One of the weirdest is that women’s faces change over the course of the menstrual cycle. When they are fertile, in other words they can fall pregnant, they become more attractive to try and attract potential mates.

Question: What is the most unusual thing you have found out about humans finding each other attractive?