Depends on what they lied about, I know... a lie is a lie!!! But if it wasn't mean't to hurt you I would just forget it. If it was about them talking behind your back or something like that, I would say that you have to think about if they are right or not. And dont let a stupid misunderstanding ruin an friendship! for example: I got in a fight with a friend and I asked my other friend if she thought the friend I was fighting with could be mean and my friend said yes. The friend I was fighting with thought that I was talking behind her back and now I am not sure if we are friends or not!
you go up to her or him and ask and if you think they are lying or you can tell that they are lying to you don't trust them or don't be there friend.
you try to get proof that she's lying and then when u get it, show it 2 ur friend
compulsively
Kleptomaniac
steal.
It is human nature when a good friend tries to tell their friend that other people are lying about her spreading gossip just as it is when a friend tells another their boyfriend or girlfriend is cheating on them. The messenger (the friend who wants to protect their friend) is the one who is going to get the worst of it, but good friends warn a friend so they are not hurt in the future. A friend that has been warned about people lying about her may think her friend is lying because of jealousy and therefore is in complete denial. Sometimes the friend in question re the people lying about her may eventually see the red lights going off and realize her friend is right or, she may end up having to learn the hard way.
Make sure your best friend isn't lying and if she isn't just talk to the boy more talk about things he likes if your friend is lying don't be their friend and try to get your man back
explain yourself
Avoid them, and choose your next best friend more carefully. There is nothing you can do about the lying. If it is about you, the people who want to believe it will, and the people who are important will not. Probably anything that you can do directly to that person will work out worse than what you have now.
get them help, counseling or certain classes
Fist to the face
Stop lying