Blackouts are very frightening...I crashed my truck into a parked car one night...have no memory of that but a vague memory of driving home with the loose fender screeching and flapping on the road. Thank God nobody was hurt.
And like kjell, countless times utterly embarrassing myself, waking up in strange places (or with completely unsavory men) when I was still doing the bar thing, or being nasty and abusive to other people with no memory except what I was told the next day.
At a meeting last week, someone told a story of someone he knew who shot and killed his girlfriend but had no memory of it...the next day when he couldn't get hold of her he started calling friends, her family, asking if they'd heard from her. He hadn't a clue what he had done, but he's in prison for it now.