Astronauts

I just thought of this good trick to play on a group of astronauts: While the astronauts are in space, everyone should glue two antennae to his or her head. Then when the astronauts return, we could tell them that the world was taken over by aliens and that they will be getting antennae soon too. After a few hours we would let the astronauts in on the joke, but not before buying all of their hats off them at bargain prices.