Not tipping but I have occasionally done some supplementary work as part of my job or otherwise that was either piece-work or hourly and, while I wouldn't have

Not tipping but I have occasionally done some supplementary work as part of my job or otherwise that was either piece-work or hourly and, while I wouldn't have wanted it as my main source of income, there was something nice about being able to bill (at an admittedly nice rate) whenever I was working on a project in any manner.