I keep telling my students to write, even if they don't have anything to say. But then, some dumbass colleague of mine teaches them the axiom, "Practise what you preach." So here I am, at the indignant behest of one of my charges.
Just wait, my instructional brethren -- I will soon enough enact my idiomatic revenge. Maybe I'll teach my class, "I know you are, but what am I?" Or my personal favourite, "Shut up, you hook-nosed bastard."