found this on the net:
5 Ways to Confuse, Worry, Or Just Scare the Bejeezus Out Of People In A Computer Lab
1) Log on, wait a sec, then get a frightened look on your face and scream, "Oh my God! They've found me!" and bolt.
2) Laugh uncontrollably for about 3 minutes, and then suddenly stop and look suspiciously at everyone that looks at you.
3) When your computer is turned off, complain to the monitor on duty that you can't get the damn thing to work. After s/he's turned it on, wait 5 minutes, turn it off again, and repeat the process for a good half hour.
4) Type frantically, often stopping to look at the person next to you evily.
5) Before anyone else is in the lab, connect each computer to a different screen than the one it's setup with.