Shiritori is a quick warm-up activity that gets the students out of their seats and thinking English. It is based on the Japanese children's game of the same name, so it doesn't require much explanation.
You can also play this game in elementary school with 5th and 6th grades in the same fashion, except they probably don't know any English words yet. To get around this problem, have them write Japanese words in Romaji, and say they can start from either the last 'character' or the last letter. For example, neko could be followed by either koma or orenji.