The term "thick-headed" suits John Ferraro just fine, because it's his very thick head that just helped him land in the Guinness Book of World Records.
Ferraro, who's earned the nickname "Hammer Head" and is also a professional wrestler known as Gino Martino, recently used his head to nail 38 nails into a wooden board in under two minutes. Ferraro is able to do it with ease because he is a medical marvel and really is thick-headed. His skull has been measured at 16 millimeters in thickness, which is more than twice that of the average human skull.
In addition to his most recent record breaking achievement, he also holds the record for most nails hammered with his head in one minute and "most concrete blocks broken on the head with a bowling ball in three minutes" with 45 blocks. (Guinness World Records)