My old man's work used to make them change their passwords once a month.
For the next 10 years, his password was a particular insulting phrase directed at the IT guys, followed by a number that would increment each time he had to change it. Got into the hundreds before he left the company.
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.
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.
For the next 10 years, his password was a particular insulting phrase directed at the IT guys, followed by a number that would increment each time he had to change it. Got into the hundreds before he left the company.