They make this product called Halt!, you can order it from nashbar. It's supposedly for dogs, has a 10 foot ranger, stores in a waterbottle cage, and leaves none of the
traces of "ulock justice"

Edit: I'm not at all serious here btw. I cannot advocate acts of aggression no matter how good they make me feel. I just thought the phrase "ulock justice" may not make it clear enough that this is a joke.