"Can't hardly wait"

My wife came on this one this morning.

If you're anxiously anticipating something do you say...

"I can't hardly wait," or

"I can hardly wait"?

Grammatically it's sort of like the confusion with "could/n't care less", but in the reverse. In this case, the thing you need to do is wait. So if can wait you'd just say "I can wait." If you can't wait, you have two choices for expressing that.

"I can't wait" or

"I can hardly (or barely or other synonym) wait"

Waiting is what you're supposed to do and you do it, but just barely.

Saying "can't hardly" is a sort of double-negative. "Can't" negates the "hardly".

Unfortunately, there are songs and movies titled "Can't Hardly Wait". But don't trusty Hollywood for grammar lessons.