one time i was playing guitar and my high e string broke, i was bored and had nothing to do, and i've heard about homemade tattoos, i promptly got alchohol to sterilize it and wrap some dental floss arround the tip of the string i've cutted, found some indian ink laying around , it was dark green, bad choice, i made like three equidistant dots, and oh god i didnt knew how flesh was so soft, the upper part of the skin was like a hard membrane, but once past that i would always pinch too deep, i had sored muscles for a good time..
edit: lol now that i read the thread, the guitar string i used wasnt sharpened, that explains its behaviour maybe