When you step in a glutinous substance, some of it will stick to your shoe and stretch as you step up. Glutinous means glue-like, or thick and sticky.
The Latin word for glue was gluten, which is now the name of a substance found in wheat. Gluten is what makes pizza or bread dough stretchy and gooey, or glutinous. If you're baking a cake, you shouldn't mix it too much or it could become glutinous, or tough. When someone is on a gluten-free diet, it means they cannot eat wheat or other grains that contain gluten.