A real dirty trick for multiplayer.
It works best in Blood Gulch and Sidewinder.
What you do is grab yourself a shotgun preferably, and you stand on the teleport pad (the ones in the middle of the map in BG or the ones that
you port to from the base in SW). You then face the direction that the people face when they port through. When the screen begins to fade
white you know you are being telefragged. Take a step back while hitting melee button. Easiest kill you ever got. They should be
confused enough to do it a few more times before they get really pissed and run out to kill you. But by that time you are long gone laughing
your head off imagining their faces swollen with rage.
More fun than anything...