I saw an episode of 20/20 about 10 years ago about theifs that would install their own sign on the street but you could lift it up and slide the lock down and off ya go. I realize that the chances of this happening to me are sooooo slim that I shouldn't worry about it, but I always check anyways like a nerd.

I recently moved to a city and learned very quickly that the savages that live around here steal pretty much anything and everything. They typically leave the frame and rear wheel if it's locked up, but they'll steal the seats, brakes, skewers, front wheel, handlebars....etc. They're brutal. U-lock and a cable to lasso around the front tire is the way I do it... even if my eyes are off the bike for 10 seconds. I'd rather waste 20 seconds per lockup than 4 days of work to pay off the stolen bike.