brownstairs is the opposite of "movin' on up." it means entering poverty or hard times, especially after experiencing financial comfort, a lofty position at a good company, or having a good relationship. it can happen after a layoff, foreclosure, or the discovery that your significant other has been cheating on you.
man number 1: damn, i had me a good job and a fine woman! my company downsized and let me go cuz of the economy and my girl found herself a man with a job. i ain't even know how i'ma make my mortage payment!
man number 2: that's whack! you totally movin' brownstairs!