According to CNBC, sales of Elmer’s glue more than doubled in December and grew overall in the second half of 2016 because of the trend. “Slime” is made with glue, water, sodium tetraborate and food coloring, and visual social media platforms like Instagram have helped boost the creation’s popularity.

Now, parents around the country are showing up to stores with shelves empty of the key slime ingredient. Elmer’s is making more of its glue products to meet the growing demand, and a spokeswoman even told CNBC that the company itself is getting in on the mania: Elmer’s is looking into its own slime recipes to “make slime even more fun and worry-free.”