And they called unto Lot, and said unto him, Where are the men which came in to thee this night? Bring them out unto us, that we may know them.
Genesis 19:5 (KJV)
The rabbis agree that Genesis 19 refers to homosexual relations, but it's clear that this isn't the "to know" that Adam and Eve experienced in Genesis 4:1. It's not a union of two who become one flesh. And it's not like the "to know" that God experiences with Abraham in Genesis 18:19, where spiritual intimacy and oneness is presented to us.
It's a threat of violence against unwilling participants. In that regard, it's more like Genesis 6:4, with similar consequences.
The Nephilim were on the earth in those days, and also afterward, when the sons of God came in to the daughters of mankind, and they bore children to them. Those were the mighty men who were of old, men of renown.
Genesis 6:4 (NASB)
After this, the Flood. After this, the Fire.