National Slime Day is observed worldwide every December 7 to celebrate the popular toy known as slime, which has been a cultural phenomenon since its introduction in the 1970s. The holiday was launched in 2022 by Ace Slime LLC in collaboration with National Day Calendar, aiming to highlight the benefits of slime for children and adults alike. Slime, a non-Newtonian fluid made from ingredients like guar gum, borax, and water, is known for its sensory benefits, improving fine motor skills and reducing anxiety. Celebrations often include playing with store-bought or homemade slime, gifting slime to children, and sharing experiences on social media using the hashtag #NationalSlimeDay. The holiday encourages creativity, as making slime can introduce kids to basic chemistry while allowing them to experiment with colors and textures.