Means to stay at parents after a drug or sexual binge. The act of chilling out and lounging without a job at parents for free usually after a intervention in which they try and save their child. Possibly can also occur after a short stint in jail.
1. Man he was so fried his parents came and put him under CRASH-DOWN so he could get his shit together.
2. David was such a mess at 30 he had to CRASH-DOWN at his parents till he landed on his feet again.