More Skywriting Above Los Angeles - BS

After Saber's graffiti sky bombing last week, there is some more writing in the sky today above Los Angeles.

Instead of having 5 jets like Saber, this had a single jet doing big huge letters.

We are not calling this BS--but those are the first two letters we saw were BS. There was a letter before the BS, but we couldn't make out what it was. It might have been a C or an S. And then a few minutes later the letters 'POP' showed up in the sky.

Not sure what this one is about?