Genesis 9

We read that after the flood that on one occasion that Noah -

"...planted a vineyard:
21 And he drank of the wine, and was drunken; and he was uncovered within his tent." (Old Testament | Genesis 9:20 - 21)

At first, I guess that one would assume that he had taken off his clothes and was naked in his tent. But with a little bit more review of the scriptures, you would have to assume that maybe someone else uncovered him or in other words took of his sacred robes or garments for -

"...Ham, the father of Canaan, saw the nakedness of his father, and told his two brethren without.
23 And Shem and Japheth took a garment, and laid it upon both their shoulders, and went backward, and covered the nakedness of their father; and their faces were backward, and they saw not their father's nakedness." (Old Testament | Genesis 9:22 - 23)

If Noah had lost sense of himself and had drunkenly removed his own clothes, you would have to assume he would have graciously given thanks to his sons. But Noah did not do that for -

"Noah awoke from his wine, and knew what his younger son had done unto him.
25 And he said, Cursed be Canaan..." (Old Testament | Genesis 9:24 - 25)

With that, you would have to assume that there is more to the story. My studies of the Old Testament is the birthright was very important. I wonder (with no evidence)if Ham had taken some sacred priesthood clothing and placed it upon his son in hopes he might acquire the birthright. That may explain Noah's sharp cursing of Canaan.