Sometimes, you probably forget the balance of your checking account, and get more money out of it than its balance. You will be charged overdraft fee from 25$ to 35$,depending on the bank. A girl in my group just made this common mistake, and she was charged 25$ overdraft fee by Bank of America. She is upset about that.
However, don't worry, you can get this fee back. I remember when I opened my account with Bank of America, they gave out a card, which allows you to get your first time overdraft fee back by presenting this card to the bank associate. I told the girl about this, and she made a call to a nice BOA agent, after the girl explained the overdraft charge appearing on her account,the agent said " sure, we will refund that money to you immediately", without asking any questions. The call took her only a couple of minutes and saved her 25$. I guess she will be more cautious next time.
Similarly, I got my late fee, over limit fee of my credit cards etc. back before by calling the customer service. It was not that hard. But still you should be more careful next time as it is not 100% guaranteed to get your fees back. But my point is that you could always call to see if they will help you out, this could save you a lot!!