Cheerleader effect

The Cheerleader effect, or group attractiveness effect is a kind of cognitive bias: People who are part of a group are seen as more attractive, than those who aren't. This observation is valid for both men and women. The effect was coined by Barney Stinson (played by Neil Patrick Harris) in American sitcom How I Met Your Mother. It was first academically described in a study done 2013, and the result is backed up by another in 2015.
Showing the effect may be difficult: The study done in 2015 was repeated, but did not show the same result. According to the research team, this may be due to cultural differences, since the new study was performed in Japan.