Lyric discussion by mad about the boy 

Cover art for Tell lyrics by Radio Dept., The

I believe it's about a male friend who is trying to protect his female best friend from her boyfriend. He knows the truth, he's caught him cheating on her. The boyfriend is trying to defend himself and try to paint a different picture, trying to explain himself by saying nothing happened. "But based on a lie that you always will/Repeat till it clings true" the man is telling him, keep saying that lie and you'll end up believing it. He'll end up believing he never did anything wrong.

"Will you keep this up/As long as you can if I don't make it stop?" The boyfriend will continue to cheat, until the friend finally confesses to his best friend about him.

Either that, or the male is in love with another male, but it just so happens to be his female best friend's boyfriend and he's trying to be loyal.

The best line throughout the whole song, "From that point of view/I get the privilege to enlighten you."