When it would be in the best interest of the party/s or person/s confronting you to leave and/or leave you alone. It should be stated with feeling. Used by youths in the North of England
When you're a girl and your close with a guy friend, and you seem like you're dating but you're not yet! If you both can tell you have feelings for each other, but neither of you wants to break the ice - You are on the fringe.
Tom: Do you see that coupleover there talking closely together? Do you think they're dating?
Melissa: No, but they are on the fringe.
Tom: Totally.