I did that all through high school and it kinda became like a habit of mine. Always sleeping in class, never studying or doing homework (since I do them all at school).
If you're talking about moral philosophy I love that
Social Contract by Rousseau touches on slavery, but it's not that big of a read. THUS, the reason I'm not going to class today. It's short but understandable. I just don't want to talk about it today.