ugly triplet 

in a group of three, the ugly triplet is the one that is left out whether it is because the other two are closer or using inside jokes. it is not necessarily unhealthy or third-wheeling, it inevitably happens in groups of three. they still connect in their own way.

"When Jeslyn and Diana are together, they always quote memes that I don't know! I'm the ugly triplet!" - Violet

ugly triplet by doubldeckrbiscut October 8, 2019