Toughest S.O.B. I've ever seen in Major League Baseball: Rickie Weeks. Watch the following,
courtesy of MLB.com.
The man takes a mid-90's fastball to the side of the face, lays on the ground for less than a minute, then GETS UP AND TAKES HIS BASE. I think the man must have balls the size and hardness of baseballs to take that one, and just shake it off!