Refers to the mash up the names of Santana and Brittany from Glee. Usually used by those who 'ship' or support a romantic relationship between the two characters. made famous (ish) by actress Naya Rivera who plays Santana when she used it at Comic-Con 2010. Also known as Brittana...
Girl 1: Oh My Gosh I hope Brittana happens this season on Glee, their characters are so meant to be together.
Girl 2: Oh haven't you heard? We're saying Santittany now since Naya Rivera referred to them as that.