Here is mine:

  I did it!
  Did I?
  No, it seems
  This index is a disease
  Why this explain query want me to die?
  Oh, I can see now... I won't cry
  I will try
  Mongodb Covered Index to fly
  But I can't lie
  It has to scan my collection hard
  better a compound one, the docs reply
  my expectations were too high