I am watching a 16 month old boy today... He is biting me, punching me in the face, and running wild?

I have a two year old, and I don't remember all of this... He wants to be held, so I hold him and he looks at me and punches me and says..SHITS! clear as a bell... I tell him "no no that is not nice and put him down and he will run back over and bite the hell out of me and laugh so hard he falls on the ground rolling... Then he gets up and attacks my 2 year old, pulling his hair, biting him so hard he is bleeding. I am at a loss... He is an absolute wild man. Is there a reason he is this way? His mom is a broom-toting *****, so I think he must be feeding off her negative energy... I just want to make it through the day with all my hair and without a trip to the ER because my son is having mive blood loss from his baby fangs...