The first lock that you put on your bike, regardless how cheesy, is about 90% effective because it forces the thief to have a tool with him. As you progress from 90% effective to 99% effective you engage in a game of one-up-man-ship with the thief which you will always eventually lose. There is no 100% effective lock.

Since you asked, I'm thinking that you aren't comfortable with your current security practice at brew pub stops. That being the case, I'd suggest carrying a heavier, more bulky locking system. The folks that you ride with - get a lock that's one step stouter than theirs.