Well... I used to do some "bad" things to myself that i couldn't really control. I know, it is very very hard, but, i have found a replacement for myself. I take a permanent marker and draw a big think black "X" on my left index fingernail. When i want to uhh.... ya.... i look at that x, and i grab a marker and make it darker and thicker. I have it there for about a month, and thats the ONLY mark i've had on myself.