One that my 12 year old son brought home from school:

Bush and Gorbachev decided to get themselves frozen for a hundred years to see
how the current political situation resolved itself. After the time was up
they were thawed, and started to read newspapers to catch up on the situation.

Gorbachev started to laugh. In response to Bushs question he said, I see that
the dollar is still getting weaker.

Then Bush started to laugh. In response to Gorbachevs question of why, he
said, I read that there is renewed fighting on the German-Chinese border.