In the pool that we've always had! That we use all the time! And the school has always had an elevator!
Click for full view; it's in HD!
Yes, it was ten years ago on this date that the Strong Bad Email "keep cool" debuted. And I've been wanting to do a picture like this for quite some time now, but I'm glad I waited this long since I get to include a couple of my newest characters in it.
EDIT 12/26/2018: I decided I hated how the water and background turned out and redid them, along with a few other things. I used this tutorial along with this brush for the trees and a way-too-involved process for the water.