This expression is similar to "what goes around, comes around" and basically means that the consequences of one's evil actions catch up in a negative way. The idea that a wrongful curse comes back to the one who curses as a "bird returns to its nest" dates back to the days of antiquity. However, it wasn't until the 19th Century that Robert Southey wrote that "curses are like a young chicken: they always come home to roost." Since then, the idea of evil men creating returns to their own door has been encapsulated in this expression.
Dude, you keep dealing drugs and you're going to get caught. When the chickens come home to roost, they will take your car, your house, and all your money!
The idea that your wrongdoings and misdeeds have caught up with you and you must be held accountable. In context this can be applied in the first or third person.
The chickens are coming home to roost, Bobby Boucher. You'll reap the fruit of your selfish ways. You're gonna lose all your fancy foosball games, and you're gonna fail your big exam, because school is THE DEVIL!