I did the same thing, once. I was at the bus station, sitting in a chair, and the vending machines were directly in front of me. I was feeling parched, and I thought to myself, "I haven't had a Mountain Dew in a long time. Probably been years." So, I fed some money into the machine, got my drink, and returned to my chair. After opening it, I took one long swig---and immediately spat it out, cartoon style. Some other people were giving me weird looks, so I said, "Now I remember why I stopped drinking this stuff; it tastes like battery acid." I put the cap back on the container and threw it in the trash can afterwards.