Some of the weddings I've been to, it's best to have a few snifters before actually turning up. There was one I had to attend years ago, the priest was about to start his gig and that was when me a few others slipped out to a nearby pub for a few beers whilst keeping an eye on the time so that we wouldn't miss the food being served.
One thing though, weddings birthday parties anniversaries etc, they can be quite easy to gatecrash especially with my well honed technique