In D.C. speak, a Fly-In is when a group hits the Congress for a day on a mission to meet with Members and talk about things that are important to their cause. As in, Hide your cheeseburgers, PETA's doing a Fly-In today!
In I Do Declare speak, a BFFly-In is when Cassie has diaper duty (she works for a company that sells diapers) out in my 'burbs for the day, and opts to stay over for the night to visit me! As in, Dan, steam the carpets, company's coming!
Though we just had a few hours together - time enough to eat dinner, gab and watch E!'s Oscar Fashion Police (a total treat to do with a friend whom I never get to share every day pleasures!) before heading to bed - it was SO much fun. I wish all my friends had jobs that had them flying in for the day!