Teething, and more teething, lol. Lots and Lots of chew toys, teach that it's not ok to chew on people. Watch carefully around small children. They mean no harm, but they are teething babies too and it hurts like crazy when they bite you or a kid. They will be teething for a while and at their hardest and losing teeth between 4 and 9 months. If they teeth on you, holler OWE and hold their mouth shut for a second. He will learn it hurts you. He will learn, it will just be a consistent teaching and learning experience for at least the first year. lol  at the end, they just like to talk with their mouth. They will put your hand in their mouth but want hurt you.  It's like them holding your hand. lol Heavy duty Rubber toys are the best like Kong and Nyla Bones for teething. They cost but will last (a little while longer, lol). It's just a natural process we have to move pass. just like babies. 

It will go by quickly. they will keep you distracted by them growing so quickly. :)