Told my mother I was heading over to help a friend with homework. Genuine plan on paper, a real subject even picked out beforehand as the supposed focus of the session.
What actually happened: two hours of talking about a show, fully absorbed, one single textbook kept open on the table purely for appearances. A prop more than a study tool, positioned strategically in case anyone walked in.
The textbook never actually got touched. Not one page turned, not one concept discussed. The appearances, I firmly believe, were fully and successfully maintained throughout, regardless of what actually happened in that room.