Answer:
While you were folding a letter you got me. Usually you will do whatever it takes to avoid me but now you can't help but find me.
I'm an animal. I love marching. I always wear a tuxedo. What am I?
You hear me speak, for I have a hard tongue. But I cannot breathe, for I have not a lung. What am I?
I am heavy forward, but backward I'm not. What am I?
Brown I am and much admired; many horses have I tried; tire a horse and worry a man; tell me this riddle if you can.
It has no top or bottom, but it can hold flesh, bones, and blood all at the same time.