I heard a legend at RPI that some students figured out just how big of a job they'd need to submit to underflow the MTS money variable and give themselves a balance of 2^24 or whatever size value it was actually using. IIRC, it was a line plotter job that would have (had they not cancelled it before actually printing and making the operators very sad, which is something you don't want to do) printed a solid black square the entire size of the paper.
The first cool hack I ever saw was on the MTS system in Ann Arbor. Students would program a login screen and leave their VT100 or Tektronix terminal. The next student would think it was the real login and provide their password. Then the hackers would move their account balance to their own account.
Yep, it sure did. I used it when I was there for my assembly language class. I remember my roommate used up his entire allotment of CPU time in one run where he accidentally had an infinite loop. (If I recall we were only allowed something like a few seconds of CPU time for the entire semester. It was typically all you needed.) He had a large print out about 50 pages long that said nothing but “The value of a is now 1,” over and over again. Luckily you could just tell the professor and he’d give you more time.