Back in high school, if you propelled a nickel into the slot of a payphone, you could get free local calls. Yes, you got the nickel back. At a washeteria, if you put a dollar into the change machine and then pressed the cancel button at just the right time, you could get your dollar back and the change too. First real hack was when I had just lost my job from a finance company (no big loss). Part of my former job was to pull credit bureaus on a sort of teletype machine that used an acoustic coupler. Got the manual for that unit with a listing of the ascii codes. I took my C=64 and developed the code I needed to log into the CB. My former employer was not smart enough to change the password. Logged in without a problem, then logged off immediately. Just doing that was revenge enough. Did not pull anyone's personal information. "Man has to know his limitations" fractured quote from a Clint Eastwood movie.