I both bought and sold weed in high school and I was never caught. Though by my senior year I had developed a nasty reputation as some kind of Stoner criminal drug dealer ne'er-do-well. I really didn't give a shit because of the social circle I ran in. My school didn't have cameras or cops and I'm pretty sure that at the very least a few of my teachers came to school baked on a regular basis. Still in a typical situation where your not an apathetic stoner criminal ne'er-do-well drug dealer you should wait until after school.