Our admin. associate, Colleen, made me take down the broken door signs this week after two math professors were flummoxed by them -- they wanted to come in to tell her that their sections of Number Theory in the fall would be taught via Moore Method, and they walked up to the door, looked at the signs, looked confused, walked away, saw students leaving the office, walked back to the door, stared at the door, and finally entered the office. Click on the title above to see the picture she took of our office doors.
Colleen wasn't too upset about the rest of the April 1 antics. (Actually, she was laughing about them most of the morning.) I stuck a mini sticky note that said "gotcha" at the bottom of her optical mouse; taped down the switch hook on the telephone so that when she picked the phone up it would still ring, joined all her paper clips together, etc. For the computer the faculty use, I moved the dock, opened up a couple of applications, took a screen shot, closed the applications, replaced the wallpaper with the screen shot, and hid the dock; however, after thinking about it for a bit, we decided that we should put the faculty computer back to normal, since we didn't think he could deal with it. (He's brilliant, but not that technologically savvy -- we can usually introduce him to one new change per year -- for example, when our note taking system migrated from a mainframe application to a web based one -- we would have been in trouble if they were to have also switched the registration system to the web at the same time.)
I am taking suggestions for next year in the comments section -- you really have to plan ahead a bit for these things.