1. Make a really long speech explaining why the argument is stupid- try and sound as wise as you can.
2. Ask them to calmly explain their side of the argument. Try and make everything as civil as possible.
3. Try and remind them of their friendship and how it can't be broken over something as stupid as an argument.
4. Start crying to distract them from the argument and also make them feel so bad that they forgive each other.