Reminds me of my first horse-riding lesson. I was just hanging on, learning how to sit right, while the trainer had the horse run in circles on that big leash.
 
Suddenly the trainer says:  
‘Ok, how about some galloping.’  
‘Wait, whaOHMYGODSTOPTHISCRAZYTHING!’
 
End of the story? I landed with my tailbone on the hard edge of the saddle.  
Now that sort of pain is quite unique. It basically goes up all the way through your spine to the head and basically knocks you out for a second or so. Or at least, makes you lose control of basically everything. Except your bladder and you sphincter, luckily.

Scoota-jockey