Meet the 'Bullet Ant,' scientific name: Paraponera clavata.
This ant, despite only measuring around 1 inch in length, has the most painful sting on the planet. One sting is roughly equivalent to 30 simultaneous bee stings in the same spot. Another comparison that has been drawn is that it feels like being shot...hence 'Bullet Ant.' (Although to be fair, I wonder how many people have been stung by the ant AND also at one point shot? 50 Cent, I've got a job for you)
The ant is used in a "coming of age" ritual for an Amazon Rainforest tribe in Brazil. Boys, starting at the age of 10, must leave a glove full of the ants on their hands for at least 10 minutes while they repeatedly sting them.
By the way, the universally accepted 'second most painful' sting belongs to a "Tarantula Hawk Wasp" (above) which is a giant wasp that kills tarantulas by immobilizing them with their sting, dragging them into their nest, laying an egg on their head and then letting their larva eat the spider while it's still alive.