The lightup sign in Kahn's post is easy to get to light up at home, you just stick a lamp under it.
When I was at University, I lived with a scouser (you can see where this is going!) and he was obsessed with nicking signs and stuff. For the two years I lived in a house with him, he managed to fill our entire living room with random bits of junk, from signs, to cones, lightup items, a workmen's tent. It was stupid.
The worst thing they nicked was one of those bollards that is usually padlocked into the ground to stop people driving cars in somewhere. It had been left up one night and it took three of them to drag it back from the University. It weighed a ton. It sat lying on our living room floor for ages, a complete waste of space.
Ou housing agency warned us about it. Then one day we got a phone call saying the owner of the house was coming around. Guy who nicked it couldn't be bothered to move it. So I ended up chucking all the signs out the back, but the bollard was too heavy to get outdoors. So instead I decided to try and move it to the unfinished basement on my own. I got down about one stair before the thing slipped and fell all the way down, smashing the bottom set of stairs.
We somehow got away with not being charged for the damage though because the basement wasn't part of the house we were living in and the agency had never inspected it before we moved in.