That watery film that greets you upon opening the yogurt for the first time, or after a long period of yogurty neglect.
Red Mango worker: "Would you like to try our new special gurt water? Our gurt water has plenty of probiotics that are great for the whole family and will leave you feeling gurty as ever."
Person: "What's gurt water?"
Anyone else: "What's gurt water?? Y'know, GURT water! I love gurt water!"