[educationonlines]

What if both parties are so drunk as to be unable to give consent, and both regret the act in the morning?

Normally I wouldn't call that rape but stupidity. Unfortunately in many instances the female gets slightly looped and the male takes advantage by buying her enough additional drinks to seal the deal.
Yes, I know it sometimes works the other way, but in general the man is using the booze to gain advantage in the situation.