I am also doing this activity I found on Pinterest and I couldn't find the pin to give the other person credit, but I saw that The Teacher Wife is doing it as well.
I have put a fun activity in various balloons in my classroom, and each balloon has a specific date on it. (I'm a bit of a control freak). That way you can prepare yourself for what activity you may want to do that day.
Some of my Activities include:
Sit by a friend at lunch
A Day without Shoes
Popsicles at recess
They may write in pen or marker all day
Sit by a friend on the field trip
Sit anywhere you want
The list could go on and I'm sure that all of you have some very creative ideas that you could replace with mine. Hopefully this just gives you a great place to start. I hope everyone has a great day!