The funniest one I've ever see is "Calibrating the radar."
The joke is even better if you don't have a radar.
Send the NOOB down the dock to shore with a cell phone. Tell them they need to walk around here and there while you track them with the radar so you can calibrate the range. Of course you can't quite get their signal, so have them reach up high with their arms, climb up on things, run around, whatever you can think of. If you get this far tell them to come back in because you just don't quite have enough signal. Send them back out with a roll of aluminum foil to hold up. Of course, that won't be enough signal either, so have them wrap their arms and body in foil and run around. Make sure somebody has a video camera going!