Did this on a bus once. My college roommate and I went to London for spring break. We randomly got on the bus to see what the suburbs were like. We only planned on staying on for an hour or so, but fell asleep and 3 hours later ended up at the end of the line in who knows where.

Thankfully there was one last bus that was headed back to Central London, or we would have been screwed. Of course it was express, so it only took 45 mins to get back.

Pretty sure they did us a favor.