There was this site to get prank software, one of them made the start button run away when the mouse gets near (Windows XP). Watched the IT teacher chase it around for about 5 min before he called the lab assistant to fix it

Cleaning up a CSS file that was becoming out of hand... Found this gem:

.main-content .panel-body .alert {
margin: -19px -16px 20px -16px;
margin: -19px -16px 00px -16px;
}

When you decide to cover for a co-worker and end up having to face a disciplinary meeting ...

up at 11:30pm finishing some work when fire alarm goes off.... waited to see if my tests passed before leaving