What's the worst pain you've ever experienced? 

For me it is definitely leg/calf cramps when I'm sleeping. I would accidentally stretch my leg in my sleep and then all of a sudden the worst cramp ensures. It honestly feels like someone has stabbed my leg and left the knife in or something. Whats worst is that I can't even scream from the pain because it's night time and everyone is sleeping :-(

I fell down the stairs at work once and couldn't walk for a few weeks -- But that's not the worst part! The worst part is, after the few weeks when I was finally able to walk again, one day at work we were heaps busy and I was rushed off my feet, then all of a sudden my leg literally felt like it snapped into two. I collapsed on the floor. (The feeling I got when it felt like my leg snapped was the worst pain I've felt!)

worst pain for me is when i tore my knee ligament during my netball training and couldn't walk for a few weeks until after i've undergone physiotherapy :(

paintball straight to the manhood during a game

I'm not even a guy but that sounds brutal.

Worse pain is when i fell from my bunk bed and landed straight on my back. I felt like i couldn't breathe lmao.

when my solar plexus hits the edge of a high platform when i try to jump up..

Being stung be a bee for me. 
(Its even more painful than getting kicked in the balls) 

Menstrual cramps.