When in your room, double lock the door by turning the deadbolt and securing the door latch. This will prevent the door from being opened by a regular key and insure your privacy. Please make sure you lock all the doors leading to the patio and insure the security bar is placed on the sliding glass door as well. Then lock yourself in the bathroom with a shotgun and put on Kevlar pajamas and a combat helmet.All right, so I made up the last bit. Still, the idea of fortifying the room in such a fashion while I'm in it really harshes my Arizona mellow. Roving bands of regular-key-wielding bandits be damned, I'm going to continue to leave the window open and wander out onto the patio in my underpants.
But onto the parsing. Yes, double lock as a verb needs a hyphen. But we've had enough hyphen talk lately. What really bumps me here is the use of insure in this context, rather than ensure. There is a lot of boring debate about how much overlap and interchangeability there can be between the two. Everyone agrees that insure is the word to use when talking about liability issues and insurance protection, but most dictionaries grant a second definition of "to make sure." I like ensure in this instance, though, for the simple reason that I like having different words mean different things. Why should insure, which has plenty to do, what with all those Allstate policies, encroach on ensure's turf? I say we close the sliding glass door between these etymological cousins and ensure the security bar is in place.