My DH and I "thought" we were going to be empty nesters in 2007, after the last of five graduated.
Only, my MIL moved in with us in 2005, I am her 24/7 caregiver; the oldest daughter decided to stay at home while attending college for the first few years. She moved out in 2008 and then we were empty nesters (except for MIL).
Then....youngest daughter came home from college for the summer and transferred college to here and has been at home for two years now....
The rule of the house is while in college they can stay here, as long as they pay $100/month for food and rent combined.
Sometimes we can kick ourselves for saying that, but eventually she will graduate!