A girl asked me to buy something for her. I bought it, and now I'm joking. What do you mean?

She may be in love with you. She asked you to buy her something just to test you, to see if you have a good impression on him or like him. But you bought something and he didn't want it, which means he has a result in mind. He is joking with you, which means he is happy. He knows what you think of him. He must be very kind to you. At this time, you can seize this opportunity to confess to her.