On those days there isn't much left to do but build a fort.
One king sized sheet, two stained tablecloths, a repurposed backstop and a handful of chip clips later, and we were in business.
We filled it with pillows, blankets, Otter Pops and Netflix streaming on the Kindle, and spent the entire afternoon in there. Didn't come out until dinner time. Then we did it all again the next day.