Today's submitter, Fangorus of <Second Life> on Durotan, has written his own explanation for this screenshot. Trust WoW Insider, it's worth reading.
"It's common knowledge that teaching ghouls, or home ghouling, is part of a Death Knight's daily routine. Teach a ghoul, you say? They are dumber than a bag of hammers, how difficult can it be? You are about to find out. Here I am about to teach my sidekick some of the finer points of etiquette in polite company. I.E. - Don't push visitors off of the edge of Dalaran. Unless you want him to."