There were three men competing for "World's Smallest" spots in the Guinness Book of World Records.
The first man said, "I have the world's smallest arm!"
The second said, "I have the world's smallest head!"
The third said, "I have the world's smallest penis!"

So, the three went to get everything measured at the Guinness HQ.

Upon leaving the building, the first man said, "Yes! I DO have the world's smallest arm!"
The second said, "Yes! I DO have the world's smallest head!"
The third walked out angrily, and shouted to the sky: "WHO THE FUCK IS JUSTIN BIEBER?!"