What was this flight attendant lingo?

I was on a completely full Southwest flight out of Chicago last night, it was the last flight of the night terminating in Minneapolis. The plane took off 15 minutes late and there seemed to be some sort of issue going on with flight attendents and a couple of passengers standing around. I was way in the back so I couldn’t tell quite what was happening, but I heard an announcent.

Something like “All fourths to the fourth”??? Then “Where is she?”

A few minutes later “All jumpers to the jump seats” and a few things of that nature every few minutes.

The two flight attendants at the rear of the plane seemed confused too.

Am I correct in that some non-revenue passengers sat down in regular cabin seats, and the flight crew were trying to find them and kick them off so that the final revenue passengers could sit down?