My current Shimano skewers piss me off for this reason.....the front one will not go around the fork when pointed in the right direction. I may flip the skewer soon to remedy that. (yes, I just said "flip it" in a non stem sense, shoot me :p )

Assuming the crook isn't carrying tools, I attach two large twist ties around the fork blade and skewer handle and pull it good and tight using two pliers. Wrap some tape on the fork to prevent marring the paint. If the skewer handle is slippery, wrap electrical tape on that too for friction. Not perfect but they can't remove it barehanded and hopefully it will discourage the pranksters.

You can also use radiator clamps in similar fashion.

knotty

Some people are just curious. I parked my bike at REI, came out later and noticed that I felt every bump in the road. Later realized that someone had locked off my front fork shock absorber that I almost always leave on. It's just a knob that turns back and forth 1/4 turn, someone was probably just playing with it. Come to think of it, some guy's toddler was stumbling around there when I was locking it up. I think sometimes people play with things and don't really know what they are or what they do, and just want to see what happens or how they work.

Just guessin'...

Thanks for this reminder to ALWAYS check the basics before EVERY ride.

Another bike rack horror story folks. You never ever use a bike rack in a mall. Those bikes are attacked by the kids who use them. You're lucky the wheels were still on the bike. Quick release and bike racks are bad news. You got off lucky.

Are you talking about a shopping mall?
I was at THE MALL. Capitol Building at one end, Washington Monument at the other, White House on the side and Smithsonian all around.
The bike rack was in front of the Sackler Gallery and next to the Smithsonian Castle, a very public place with NPS police around. Plus there is a food concession a few feet from the rack (I don't know how helpful they'd be, but it's something of a thief deterrent). I've locked up at many times before with no problem.

Forgive him, they have no museums in Jersey, only shopping malls. ;)