She had a recurring 'nightmare' [=she had the same bad dream many times] about losing her job.
Losing a child is every parent's 'worst nightmare'. [=the thing every parent fears most]
Mommy, I had a really scary 'nightmare'.
(..) Bam, we're in that ditch. Yeah, bam, I'm like, what the hell? You know? Yes, and my coffee mug. Coffee? My mug of coffee? It spills all over my pants. I mean, just... a nightmare. Dude, you so need GPS. I mean, for real. Like I said, we couldn't be more grateful. Can't we just dump 'em here? (..)2008 TvShow: Breaking Bad Title: Cat's in the Bag... Season: 1 Episode 2