I particularly enjoy showing people the little known "goes to" operator:

  -->

with example code such as this:

  #include <stdio.h>
  int main()
  {
     int x = 10;
     while( x --> 0 ) // read "while x goes to zero"
     {
       printf("%d ", x);
     }
  }

The above code compiles and runs, listing the numbers from 9 to 0.

For more details on this little known operator, I recommend this stack overflow question:

http://stackoverflow.com/questions/1642028/what-is-the-name-...

Always a classic.