Oregon Trail forever, dude
Oregon Trail that my school had was written in Applesoft BASIC. This was very fun, because Grishnash and I were quite proficient in Applesoft BASIC back in our elementary school days. This meant that we could hack it and make it say naughty things to the player. Then the teacher found out Oregon Trail had been vandalized. Naturally, she asked Grishnash and I, the most knowledgeable computer geeks in the class, if we could fix it. Of course we obliged. Looking back, I suspect our teacher new we were the original defacers, but we never really got in trouble for it because we were otherwise pretty well behaved.