I usually write with both red and black markers whenever I teach. Every room here has white boards, so it really is very handy to use different colors to emphasize different things. But sometimes, I just pick up any random marker and write whatever I need to. I have made the mistake a couple of times of writing a few of the kids names in red while teaching. With this usually comes shouts and plenty of protesting. The first time it happened, I couldn't figure out what all the kids were so upset for. But soon after, figured things out. Now, I just forget every once in a while and scare the kids for a second until I remember and quickly erase whoever's name it is and re-write it in black. Writing a persons name in red here means the person is dead.