National Splurge Day is celebrated on the 18th of June of each year. According to Fast Company, “Chicago writer and ‘eventologist’ Adrienne Sioux Koopersmith may have created this fake holiday on a lark, but that hasn’t stopped people–and companies–from marking it.”
To splurge is to indulge yourself. You can also go on a splurge if you spend a lot of act extravagantly in another way.
Anyone might have a cupcake. If you have 10 cupcakes, that’s a splurge. When you go on a splurge or a splurging, it usually applies to money. Splurging happens when you see a lot of things you want — or even one very expensive thing — and buy it, even though you might not be able to afford it. When you splurge, you’re going wild in some way. A splurge is sometimes called a binge. (vocabulary.com)