leave my abs out of this

So...

I was on my way out, after pumping some iron at gym...

When some random unknown gym instructor asks:

"Did you remember to do your abs today?"

Now, let this sink in, it took me a while...what did he mean by that? Any suggestions?

And having an analytical nature, I was trying to figure it all out.

But before I had time to figure it out, I was told this by another random dude at gym, the next day:

"Have you tried this ab machine before?" While pointing to the ab machine he was using.