A game similar to nickteacher's Zombie Game, though modified by one of my teachers to make it simpler.
Decide on a focus question and go over the question and answer. This question should be something with multiple possible answers and not a yes/no question. "What ~ do you like?" is always good, but other questions also work for different grades. Have the students close their eyes and tap a few on the shoulders (I usually do 2-4). These students are Ghosts. Ghosts answer questions using the word "ghost" (I do the same thing in Zombie Game to make it easier). For example, if the question is "What food do you like?" then ghosts answer "I like ghost food" or something similarly obvious. The students walk around and ask each other the question and say their answer for about 2-5 minutes. At the end, students can raise their hand and point out 1 person who is a ghost. I usually write a big number on the board that I erase and change for each correct answer to keep track of how many ghosts are left to be found.
This is a little easier than Zombie Game because they don't have to ever change their answer, so it's good for lower level classes, but since it's similar, I've also included my Keynotes slides for 2 versions of Zombie Game as well.