Answer:
I'm not man's best friend, I'm their enemy, I can mark your end, yet you do not see me, I am very small, but very tough, If you have me, then you have it rough.
What has two legs but doesn't walk?
I am mother and father, but never birth or nurse. I'm rarely still, but I never wander.
What is full of holes but still holds water
What is full of holes, but can still hold a lot of water?
What never gets any wetter no matter how hard it rains?
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?