Coffee lover

My son is 6 and has DS. He is really into impulsive behaviors, like when he walks past people in a store or a restaurant, he reaches out to swat at them or if he sees a toddler he'll try to push them over. He isn't angry when he does this. It seems to be just because he can. I realize this is quite common for kids w/DS but do they outgrow it? What techniques help to reduce these behaviors?