When I was in middle school we had a crazy mid-winter thaw and an intense rain that froze the snow hard enough that you could walk and even jump on it. Actually what we used it for was sledding, sans sled. We'd just plop down at the top of the hill and slide down on our butts. It was a hoot...or at least the down part was. I haven't seen those conditions since, but in the age of climate change all bets are off.
When I was in middle school, mountain bikes were quite new and fatbikes were more than a decade off. So at the time it didn't occur to me to try and ride a bike on that icy snow.