Happy Golden Week Ya'll.
Today our phrase to help you with your English ability is, What can I tell you?
This means that something can't be explained further. There is no explainable reason.
Example 1
A. How did you get 900 on your TOEIC test and not study?
B. What can I tell you? I am just good at English.
Example 2
A. So, you just took my car without telling me and then had an accident??
B. What can I tell you? I made a mistake and I'm sorry.