A hook on the outside of the door.
When my son had just started Kindergarten we still put a baby gate up on his door sometimes to slow him down. His room was right by ours. One morning he had climbed over and was sleeping in the hallway right in front of our door. I picked him up and put him on the floor in his room. He must have squirmed and hit his leg on the gate. Got a call from school nurse... "He has a scratch, what happened?". Apparently he told them I threw him over the gate and they are picturing like a fence in front of the house or something. Ended up with child welfare guy at the house to check us out. He pretty much got a laugh out of it, but pissed me off they can be in your business that easy. Then you hear of kids abused for years...:wtf: