What's the most venomous critter you've been bitten/stung by?

Fucking hell! Did your bite require antivenom?

I didn't seek medical help, this happened when I was a kid. My brother and I would snake hunt for fun and look for different species to catch. When this happened I was afraid to tell my parents thinking they would put an end to our adventures, so I made my brother promise to keep silent. It is a pit viper, but thankfully the venom isn't overly toxic. It was very painful and I felt horribly sick for a few days.