I once made a hack (template mod actually) where only for the board owner (i was part of a team of admins), the whole index page would just turn upside down/mirrored whenever his mousepointer enter the area. It was impossible almost to click on any link like that.
Another one was (again for a limited number of users) a random Usertitle (lol, i made up some funny ones, tailored for each user), tht would change every 10 minutes. We ended up keeping that one longer then planned. At first the board owner and 1 other admin where out victims. They didn't have much programming knowledge. They would spit through the amdin logs to see who change their usertitle for days, but no luck