Hi, I was curious as to finding new messy substances to play with. I've already used mud, oil, lube, syrup, and fake semen. What else is there that I could try?
Probably my favorite substance, "substance" being something other than a common substance or recipe used for slime, would actually be nacho cheese. I can't stand the stuff on my food but for getting messy it is super gooey, feels amazing, and I can tolerate a little bit of it getting in my mouth. Chocolate is a close second and also tastes a lot better, and molasses was actually really fun too, and not nearly as hard to clean off than I thought it would be.
Otherwise, cake batter and slightly thinned out pudding make good, easy slime and are tasty if you have a sweet tooth. Flour and water makes for super cheap slime as well but while it is technically edible, you'll want to make sure you seal your lips extra tight if you use that.
Wish they smelled and tasted better, but I love eggs. Slimy, run down inside clothes, coat and cling them well; fill shoes and slip them on; smash on head and feel them run down face and scalp; fill pockets and smash; open fly, crack and drop them in...