I was doing the same at one point, albeit it only lasted 5 years before I changed employers. Didnt even had to rotate the numbers, I could always come up with new and colorful insults for the nameless IT group. Which ironically I remember perfectly.

I'm reasonably certain that I'm not your father but I used to do that too - although I don't think I made it into the hundreds.

I had a coworker that would type in something random as his new password, then immediately fail to login three times in a row so his account would get locked. To fix this the sysadmin would reset the password, and allow you to choose a new password... and on the no-repeated-passwords policy did not apply to the magical reset dialog. So he would then reset it to his old password.