A couple of weeks ago a friend of mine pointed me in the direction of a really funny Ellen DeGeneres video. In it, Ellen makes fun of the Bic for Her pens and the fact that they are more expensive than regular Bic pens. Having an interesting video, I started looking for an article I could use it with and found out that women pay more than men do for a variety of products. This is now called pink tax, which refers to the premium women pay for certain products (that are generally pink).
This is the lesson I taught to an adult student, but it can probably be used with young adults (16-18 year-olds) as well.