In Leviticus 18, the phrase "uncover the nakedness" appears 11 times as a euphemism or idiom for "having sexual intercourse". E.g. Leviticus 18:
Noah uncovered his nakedness due to being drunk. Shem and Japheth covered his nakedness.
Gill commented:
See also Why did Noah Curse Canaan and not Ham when it was Ham who did wrong?.
Did any of the sons of Noah uncover the nakedness of Noah (or having sex with Noah's wife) in Genesis 18:7 You shall not uncover the nakedness of your father, which is the nakedness of your mother; she is your mother, you shall not uncover her nakedness.
No one uncovered Noah's nakedness; he did it himself.21 He drank of the wine and became drunk and lay uncovered in his tent.
Ham saw the nakedness. Ham did not uncover the nakedness of his father.22 And Ham, the father of Canaan, saw the nakedness of his father and told his two brothers outside.
Neither Shem nor Japheth uncovers the nakedness of his father.23 Then Shem and Japheth took a garment, laid it on both their shoulders, and walked backward and covered the nakedness of their father.
Ham saw his father's nakedness. Shem and Japheth did not see their father's nakedness.Their faces were turned backward, and they did not see their father’s nakedness.
Noah uncovered his nakedness due to being drunk. Shem and Japheth covered his nakedness.
Gill commented:
Ham did not uncover the nakedness of his father.some will have it that he[Ham] committed incest with his father's wife; but these things are said without foundation
See also Why did Noah Curse Canaan and not Ham when it was Ham who did wrong?.