Lot heads off and settles in the hills, in a cave with his two daughters.
The daughters are worried that they're going to be old, unmarried hags, so they hatch a plan to get their father drunk and "lie with him" in order to preserve their lineage.
Yes, that means what you think it means.
Sure enough, they get him drunk and they both manage to have sex with him without him noticing.
They both become pregnant. The elder's son is named Moab, which means something like, "from daddy." Ick. The younger's son is named Benammi, which means something like, "son of my own folk." Ick again.
These guys turn out to be Israel's enemies.
One last thing: Abraham pulls a repeat of the sister-wife trick, this time with Abimelech.