or something really stinky and sticky on it so when they grab it, it gets all over them.

... because I like your suggestions.

If you deliberately do something that actually causes an injury, it can be a criminal act.

I'd rather get their name & picture in the paper, and get them a fine & some community service.

Mix peppers and some oil in a food processor. Thin it with water and brush it on the borders of the signs.

I will guarantee the thieves will never forget the outcome.

the one on the other side is a rather paranoid "economic conservative."

I've noticed that a lot of RW paranoia is mostly projection. They know what shitheads they are, and assume everyone else is the same.

so I know it was not the wind blowing the plastic sleeve off. Cowards.