I've done this too. Feel drunk and then extremely nauseas. It's a VERY uncomfortable feeling. Think you're gonna die, but thankfully you don't.
It's a mistake you don't want to make very often that's for sure. When I did it I was seriously worried that I might OD I felt so awful. I've wondered a time or two since then if I've done it again and thankfully haven't to my benefit.
Lets hope it doesn't happen again.