This expression is usually yelled by a third party when someone gets chumped out by someone else. Typically this is a heckle that adds insult to insult. Similar to shouting "CHUMPED" or "BURNED" or something like that. This usually results in an uproar of laughter.
It is a reference to the face of the person who just got told. Their face may appear to be tight because they want to cry or are extremely mad.
Person A: "How dare you give me an F on this assignment"
Person B: "HOW DARE I?!? I'LL TELL YOU HOW!! I WENT TO COLLEGE AND GOT A MASTER'S IN EDUCATION YOU LITTLE PUNK"
Person C: "TIGHT FACE!!!!!"