80% Glycerol stock is what it sounds like, and is used for freezing down yeast strains, among other things. If you are working with Mark, the stock is kept above his bench on the shelf labeled Buffers and Solutions.
If you are not working with Mark, the stock is located across Bhumil's bench where lab stocks are kept. (lower shelf).
GLYCEROL P/N: Sigma-Aldrich, G7893-2L