To start this out... I'm a KLUTZ!
Let me tell you about my Wednesday morning. I was walking down the stairs to go to work. It was about 7:30. I was carrying a puppy, this way he couldn't wander and piddle. Walking down the stairs, walking down the stairs, everyone in the house is sleeping, walking down the stairs. And just like you'd see in a cartoon, I fell. My feet came out from under me and I landed on my butt on a step (carpeted luckily), me head fell back and hit the edge of a step, and the puppy was airborne. I thought I was going to have a headache for the rest of the day. Nope. That went away. But I think I may have fractured my bum bone (the coccyx). It hurts. It's hurts to sit, stand from sitting, squat, bend over, walk, well, you get the picture.
So, moral of the story, no matter how bubbly you think your bum is, if you fall on it just right no amount of padding is going to save you.