Only allow chats when reps are availabe to accept

I would like rather than chats going into a queue and waiting for the next available rep to answer - to have an option that we could go busy or shut if off for new chats temporarily when all my reps are on a chat. Sometime's I have 10-15 chats waiting during lunch times and all my reps are already on a chat and no one is available to answer new chats coming in.