In high school our computer class was in BASIC. They taught us to swap two variables A & B like this:

  h = a
  a = b
  b = h

But I knew the BASIC we used had the SWAP command. On an exam, I used SWAP A,B instead of the above. I got the lowest passing score, a 70%, and the teacher wrote, "Do it our way please". No thanks Mrs. Mott, I'll take the 70.