> The TA [...] asked during the lecture where he was, if he could say something about his grandfather, it turns out he played [hooky] from the class to work on

> The TA [...] asked during the lecture where he was, if he could say something about his grandfather, it turns out he played [hooky] from the class to work on something else, embarrassing! If the "working on something else" means "working on some hard research problem", this is not embarrassing, but stylish. :-)