I remember itade me learn how fat worked, then I would use debug to make recursive directory trees with large files in them so a dir /s would terminate at max depth with a huge aize reported. I used it to make people in my HS cs class think I had found really good floppy disks.

I lost tons of work when playing with toy assembly language programs in DOS, when I would save and compile and run it and it did something to crash necessitating a reboot, faster than SmartDrive would write the cache to disk. Particularly for anything crash-prone like messing with hooking interrupt vectors.