Last summer I was at Alice's Restaurant at dusk helping a friend deal with a flat tire he'd gotten during our ride. We were both busily trying to solve the problem, calling AAA and nearby friends and a tow truck and etc. when a biker rode up too fast and too close to us, stopped suddenly, almost dropped his bike, parked it, and wobbled across the parking lot to the restaurant. Yes, he was clearly so drunk he could hardly walk.
Why did I do nothing? Well, at the time I was busy helping my friend with his problem and so it was easily dismissed. But then, maybe I was simply avoiding the discomfort of the drama it would have certainly created.
But later, as I was riding home, I realized that I had a lot more discomfort around the *inaction* I took. I hate wondering if he hurt himself or others and I know that I should have done something.
When this came up in conversation with my friend Greg, he (not shy of confrontation) says he would have followed him in to find his friends or the restaurant manager. Failing to elicit a satisfactory response, he says he would have disconnected the spark plug wires on the guy's bike. "You know how hard it is to figure out your engine's firing order when you're drunk," he reasoned. Good tactic, Greg! Now I'm thinking we could have just moved the guy's bike back behind the building under the blackberry bushes. (For sure he didn't lock his steering.) Or hey, maybe I could have locked my Cryptonite on his tires. A few bucks lost, but better than life, no?
So next time I will take action. But I'm curious. Have you ever encountered a situation like this and, if so, what did you do or not do? Barring that, any creative brainstorming?

I think its best to notify the manager of the establishment or place an anonymous phone call to the police notifying them of the situation.
Keep in mind that while your intentions may be for the best, tinkering with someone else’s bike in order to prevent them from riding it, could result in unforeseen damages, harm to the rider, or harm to others. If you tinkered with the bike which was then driven and involved in an accident, you could be held accountable.
I’m also thinking the anonymous phone call to the authorities is the bset choice. A D.U.I. is a hard lesson, but it is much less hard than a D.O.A lesson.
Take the direct approach.
Don’t throw the responsibility of your actions or lack of action to the police.