I've always thrown away my drinks if I leave it alone without someone I trust watching it. I don't have to worry about it much anymore, since I always go out with people I trust. I used to go out alone though before I met my husband, while living in Hawaii. I definitely didn't drink anything I left then. I almost always just took my drinks with me or simply figured it wasn't worth it. Probably one of the reasons I drank a lot of water and soda. Cheaper and I knew what I was supposed to feel like at the end of the night.