Swill was a mineral water that came from a lake and had the consistency of a gel. In the add, Bill Murray purs some into a glass and extracts a pull tab from the mineral laden goo.
I stepped on a pull tab in a lake near here last year. I think those things were banned in the early 70s. So, around forty years ago, someone dropped it and it lay in wait for me ever since. Talk about a nostalgia trip!