Many adjunct professors are people who have full-time jobs doing something else. A friend of mine did this one semester to make some extra money. He worked full-time as a structural engineer, but took a long lunch three days a week to teach Introduction to Statics at the university we both attended. He said it was fun to do for one semester, but he computed that he was only making about $10/hour when you included the time to prepare for lectures and grade papers.