To open the door to the bathroom and walk away while someone is sitting on the toilet...preferably during a dinner party or other social gathering. The effect is to both embarrass and paralyze the person being holodecked. Crew members of StarTrek probably do this to new crew members. They trick the noob into thinking that the holodeck is actually a bathroom, waiting for the newbie to get settled into a grump, then shutting off the program and opening the door for everyone to laugh at.
Dude, gather everybody up and meet me in the hallway...I think Missy needs a good holodecking.