I used to work at a company that had its own teaching academy.

They once sent out a sectionwide e-mail announcing a new mobile app development course. One of my coworkers responded with a "thanks, I need that badly!" to which, amusingly, he was told that he was to be the teacher!.

Edit: I have found that "The best way to learn is to teach" (attributed to Frank Oppenheimer) is quite true.