Extremely stringy clear slime. You've seen this kind of stuff in the mouths of many famous creatures including the Monster in Alien. Super stringy consistency simulates stringy saliva and body secretions. Color with food-color or water-soluble makeup or stage blood. Non-toxic.
Stringy Slyme with Chunks
Same formula as the above, but we've added little pieces of polymer to simulate chunks of clear tissue (or whatever you want to imagine it to be.) Non-toxic.