Hey, remember when I loaned you that $100 with a 10% interest rate?
Sure I do.
Well, since inflation is at 10% now, I decided I'm changing the interest rate to 15%.
Why would you do that? Thats not fair!
Because of The Fisher Effect. If I kept the 10% interest rate with 10% inflation, I would make no return! Instead, I'll have to charge 15% interest rate on that $100 to get a 5% return! 
Well that makes sense, but did you have to take me out fishing just to tell me?