An individual, probably a millennial, who wants to enjoy a night out on the town but doesn't want to spend any money so he or she utilizes event platforms like Eventbrite or Meetup to find parties offering open bars, free food and/or activities. When a britecrawler visits several of these events in the span of a single evening its what's known as a britecrawl.
"I was told this whiskey tasting was a formal affair. What's with the cool, plaid-shirted mustachioed guy."
"I don't think he was on the original invite list; but his knowing yet lackadaisical countenance that seems to scream 'I'm internet savvy!' tells me he's probably a britecrawler."