You cross over Delightful Scenic Way Awesome Pass somewhere in the backcountry.
As you set down your sweaty pack caked with salt, shmutz, and grit, you notice a pile of snow near or at the top of the pass.
Having a little water in your bottle, you top off the bottle with a bit of snow, too. Or you add a little water and snow to a bowl.
Mix with the flavoring of your choice (lemonade powder? Cocoa and Coffee packets? EmergenC? A little something-something extra at the end of the day to make an adult libation?), and you just made a backcountry slushy.
Easy to make.
And oh so satisfying for kids.
Or kids at heart.