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.