We read about the incident in which the angels show up in Lot's house in S'dom.. Lot brings them in. The people of the town hear that Lot has guests and they come to "arrest" them. It is unclear what they really wanted to do with the guests, some opinions say sodomistic purposes, others say torture. Lot says in 19:8 not to take the guests rather I have two daughters, take them.
How could Lot offer his daughters to them? If you say he felt responsible for hsi guests and could not give them up at any cost (as Rashi says) and therefore he had to offer his daughters in their places, should he not feel responsible for his daughters well being as well? He should have offered himself in their place!
Maybe he knew they would not take him because he was one of them, so the only alternative was to offer his daughters. I just fail to understand how a father could offer his daughters to such an evil plan..