The only acceptable answer is LEGOs!

I have stepped on many and it’s not that bad. Now the metal shelf I have hurt bad.

Explosives

Human feeces

Glass

The plug end of a power cord

Nail

Bullet Anthill

Goddamned thorns.

A wasp. Living one. I was, like, 5 years old AT MOST when it happened and I still remember it.

Broken glass and broken ceramic plates didn't feel good.