I have just successfully trolled myself.
I left a practical joke on a computer that has more than 1 user and just got utterly confused months later.
See if you can spot the problem:
For anyone wondering what is wrong, here is the prank's origin:
http://xkcd.com/1031/
Practical joke gone wrong
Practical joke gone wrong
mortimermcmirestinks wrote: Now I wish MoffD wasn't allergic to me.
Levellass wrote:You're an evil man.