Locked the gate

Last night my sister left and she didn't lock the gate probably. I am shocked to see that she didn't even lock the door. When I open the door and I wanted to check on the gate. What I see? The gate is not locked at all, this is scary lucky is that I found out about it soon enough. Who knows what will happen if I check on the gate hours later.

I told her about it today and she told me that its my job to check whether she locked the gate or not. What?! That's the craziest thing I ever hear, everybody knows that who ever go last has to check on the locks.

If something bad happened to me or my home. It will be too late to regret then.