Had better

[meskete]

I think there's just a spelling problem.
The correct structure includes had:
I'd better go now. You'd better hurry.
However, we often don't pronounce the 'd - as we don't pronounce t or d in many other cases:
mustn't, I can't bear/stand/go..., mind the gap, etc.
Sometime you can really hear that slight difference between I'd better and I better but it's such a small thing that it can easily get lost. Still, it shouldn't be left out in writing

[gabber]

"had better" is what [some] grammarians call a modal idiom. It means "should."

[mara_ce]

Originally Posted by Tdol

Does anyone really understand this structure? To be honest, it escapes me.

Had better refers to present or future time, and gives advice about how to stop something going wrong.

I think you'd better leave now. (Before it is too late)
You'd better not drive. (It might be dangerous)

[Huda-M]

'Cause we say - You had better do it, so, i think it will be you had better NOT do it. You had not better do it looks a bit sensless to me................

[xpert]

had better not

[GreyMan]

Originally Posted by gabber

"had better" is what [some] grammarians call a modal idiom. It means "should."

That's interesting. I though it didn't fit in with any grammatical pattern, even though the meaning is clear.