The issues with doing something about thieves are these:
#1. Motorcycle thieves are not exclusively motorcycle thieves.
#2. Usually, thieves are involved with drugs.
#3. Drugs usually involve weapons.
#3 is what is going to get you into massive ****. It's one thing when you're just punking off a bunch of kids staring you down at STC, it's another when it's organized crime. Honestly, the only thing I can think of is, seriously, Semtex.
If you know anyone in an university or college in some kind of chemistry program, explosives are not very hard to make (or smuggle out). There are MASSIVE flaws w/ this solution tho:
a. You may kill yourself if you forget to disarm it.
b. Accidental detonation will lead to...well, stuff blowing up.
c. You will probably get jail time.
So all you can do is let your imagination do the work, day dream about dragging their heads across the wall like Hulk does because I don't think there is anything we can ever do =/