Idiom: to grill someone; used as a verb
Theresa was really grilling Harry on their first date. She was sure asking him all these questions about his preferences. He eventuall had to ask her to stop.
When Janice said she hadn't done her homework because she had to go to the hospital the night before, the teacher grilled her on what happened. The teacher asked for so many details, Janice finally gave up and was honest, explaining that she went to a movie.
Meaning: To "grill" someone means to ask that person many questions, similar to a cross-examination in a courtroom. In the first example/illustration above, Harry was grilled by his date; he thought her questions were excessive. In the second example, Janice is grilled by her teacher, and she eventually admitted that she was lying.