Zookeeper

Use this game after you've introduced some new vocabulary.
Suppose you have 12 words (and thus 12 flash cards) and 12 students.
Give each student a flashcard, and stand in the middle with a flyswatter.
One student starts by saying his card and some other student's card.
That student says her card and some other student's card. Repeat.
If you can hit the student whose turn it is on the head, you and that student switch places. Start saying cards again.

Variations

If you have more people than cards, make teams and students rotate after they speak.
For younger students, only call out the new card.
Students point to the card they are saying. This makes it easier for the person in the middle to know where to look.