Maybe its a message from Robert Bowling himself, giving you commands. You should do exactly as it says.
:carling:
On a more serious note, I have encountered this aswell. If I remember correctly, it happened when I was spamming the change weapon button. I think it also comes up in theatre mode, along with other assorted theatre glitches/bugs/you name it.
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I haven't seen it like that before, and I'm sure you know, but if a team calls in 3 UAV's it turns into an advanced UAV.
Perhaps those who have a UAV in that Killstreak slot, are being told that they're UAV will be an advanced one? Im not too positive.
Could have been something they put in through a hotfix or something.
You probably called in an Advanced UAV while there was a daily challenge available for it. The challenge requirement/description sometimes appears there when you finish it because... well, it's a glitch.