<human>: Can you provide a brief overview of the text?

This happened yesterday at school. It was our friend's birthday, so at lunch, two other friends and I decided to send him a happy birthday snapchat (he's in college; we're in high school).  One kid took out his phone and began to record a video. He said "hey, happy birthday" and the other friend and I said "and go fuck yourself" in unison. As we were making this snapchat, we didn't realize that our principal was walking up behind us with a woman whom he was giving a tour. It turned out this woman was an important sponsor of the school. They seemed to ignore us and went into the cafeteria and a few minutes later came out, and the woman left. But then our principal called us into his office.  He told us that he had been preparing for several days to impress the woman.  He had just explained to her that sitting outside for lunch was a senior class privilege... and then immediately she heard a group of those seniors say "go fuck yourself." He asked us to write a letter to the woman apologizing for the incident. He wasn't mad at us; he just seemed very, very sad. So sad, in fact, that he apparently couldn't think of a way to actually punish us.
<bot>: My friends and I indirectly told our principal and a woman who was going to give money to the school to go fuck themselves.