I stumbled upon this website today, a list of all the (supposedly real) national 'days' for every month. (I was born on National Applesauce Cake Day. I kid you not.) Not only was it fun to look at, but it served as the basis for this week's prompt: invent a holiday. It can be silly or serious, something obscure that no one knew about or a well-known tradition in a made-up world, anything that you want. You can just write about the holiday, you can show your characters celebrating it, you can make up its origins, or anything else you can think of involving it.
If you don't want to invent a new holiday, make up a family tradition that your characters follow every week, month, year, etc. Tell the story of how it started or show the family participating in it. Have fun with the prompt and don't ignore any of the ideas that come to you because they sound silly. Just enjoy.