One time on a status message I posted on Facebook, one of my friends commented on it with that phrase, and I have no idea what it means, and I don't even remember what that particular status message was about.

I think its a reference to Inception, though I don't understand the context.

Ooooh... that's that movie where they go into people's brains for some reason? Haven't seen it, but this makes sense if that's what it is!

Pop culture reference pools are fragmenting. So many alternatives. One of these days, people at the office will be relegated to commenting on the weather because they won't even have the local news in common.