All the times I was a passenger, I never knew there was an official name for it. (I had to look up "pillion".)
At first I thought it was sort of a joke - I was just playing around, goofing off, like being in the backseat of a car. Luckily, I was riding behind an experienced rider who taught me that it was my responsibility to pay attention and know what was happening so I was not working against him. I need to lean with him in the corners, keep my legs out of his way, not be a distraction (picture cutesy little tickles and gropes), and not make sudden movements that could affect our balance. Now I save my games for more appropriate places.