I know this is going to sound stupid, but I have no idea how to get this sticker off my car. I bought it used and the girl who had it before put this skull sticker on my rear window. It is a crappy one, and I tried to peel it off but it won't budge. I used my fingernail, but am afraid to use anything else, I dont wanna scratch the glass. I also tried goo gone, but that did nothing. Anyone have any suggestions?