I was a hair's breadth away from expulsion too - exfiltrated .sam files from a PC in the library on a 3.5" floppy. Seems to be quite common experience judging by this thread.
Why did we all get caught? Smart enough to figure that out in your teens, dumb enough to think you can get away with it...
In my case I was operating with a dumbass friend who left a "calling card" on one of the compromised machines.