A flophouse may also be the home owned by the parents of a college student, who after being away at college, wishes to live as if he/she is still at college (e.g. staying out all night, returning just to crash at mom and dad's house, then leaving again), rather than conforming to the pre-college rules.
Dude: (Talking to someone passed out face first on the floor of his college apartment) Hey man, who the hell are you? What do you think this is, a flophouse??
Bro: Sorry dude, I must have passed out for a minute.
Mom: Where have you BEEN for the last three days? You come home just to sleep?? What do you think this is, a flophouse??!!
Son: What's your problem? I'm an adult now!
The expanded version refers to teenagers that think they can come
and go in their parent's home, sleep, eat, shower, and contribute nothing to
cleaning up after themselves
Dad: What can we do? He's using our home as his flop house.
Brad: What do you think this is, a flop house?