I lock mine, regardless. In the garage, out of the garage, out with the SCJB group, where ever. Just an east coast habit I got into. Built a nice utility trailer back east years ago. Brought it home from the shop, parked it in the street, GONE at 6AM the next morning. Nowadays, between me, and the neighbors, busted 3 guys trying to hook onto my "In Process" 26' with chains, whatever since I lock all the hitches (Don't use cheap ones, the tamper, bolt cutter proof ones are the BESTEST!

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I even lock the hitch in my receiver! Back east, I had a beautiful Class 4 (Weight Distribution bar mounts 'cuz I towed backhoes and stuff) disappear when I was in a grocery store for less than 5 minutes to get cigarettes! $500 hitch back then, dunno what it'd cost me today. I guarantee the rednecks that took it had no idea what it was for UNLESS it was to move their home.......
Not that I don't trust you guys! Far from it! But with Craig's list, Ebay, etc, easy stuff like this turns into cash quick. Boats? They dpn't need no stinkin' boats! But that tandem trailer would haul at LEAST 5 lawnmowers and a handful of leaf blowers!..........

Ray