A lot of times, you wake up, but only partially. You're awake enough to think something like "Get back in the bed", but you're asleep enough to not remember it.
It's a fairly common thing, I think.
And... as for the dumpster...
I'll just say I've made some stupid decisions in my life.
I don't condone drinking in anyway, and I wouldn't recommend doing it.
It's stupid. Unhealthy. And crap happens - such as waking up in a dumpster a few hundred yards away from where you were originally.