You are the assistant of your town's chief detective

It's currently 11 pm and you're standing outside the office with a cup of coffee

You stand there for a while, when you finally decide to go in, when you get inside you see that the chief detective is still working and overlooking some paperwork

You go to her desk and put the coffee on her desk, she notices you and looks surprised

"Oh, thanks for the coffee, but why didn't you go home already?"