This is Arteval Duarte, a Brazilian nicknamed the "Ninja of Serpents" for his aptitude in handling snakes, which he has been doing for over 15 years.

Here he is in the city of Pará shoving a live banded cat-eyed snake and a pinktoe tarantula into his mouth. 

According to Duarte's technique, if you are going to perform such a stunt, you should wrap the snake around the spider first, and then place both in your mouth.