It's fucking bs and pisses me off every time I hear or read it. Usually said/written by women who don't even have abs.
Abs are muscles. If you lose your excess fat, it doesn't mean you'll have an epic 6-8pack. You still need to work/build your ab muscles. In many cases, (natty) chicks diet down to decent bf levels and still don't have visible abs. They just get that slight line down the middle of their stomachs. Their ab muscles are too small to "pop out" of their stomach wall.
I've had abs all my life (after around 4yoa). Just in the last couple years they've started to fade a bit. Not because of age or fat (I'm just as lean). It's because I don't play sport as often as I used to and have only worked my abs (directly) maybe 2-3 times (in the last couple years).
Also, from what I remember, you can get a bit of an "ab pump" just like your other muscles (for those of you who didn't know). They will bulge out more after an ab workout. So I think all you competitive thong warriors should do a quick set or 3 of situps or whatever else before going on stage.
Now for something random; I found a bottle of Cialis at my work today. And I don't work in a gym or anything like that. Only a few pills though.