To be given a job, responsiblity, etc. Abruptly and with little notice. Generally last minute and annoying.
Example of fall ass backwards:
Mom: I'm leaving watch the baby! Bye!!!
Kid: WHAT?!? No I can't even clean this thing if it shits the bed!!!
Mom: I tough you a while ago.
Kid: that was my sister!
Mom:*speeds off in car*
Governor Patterson of new York.