[2ndDivisionVet]

What is being “kettled” I wonder?

[McGruff]

Maybe she meant "cattled".

[Captain Compassion]

As per Urban Dictionary - “Kettling is a tactic used by police to try to suppress peaceful demonstrations by corralling protesters and refusing to let them go.”

[BlueLancer]

""I was arrested when the police kettled the crowd," Taylor says ... "The MPD closed off an entire city block and arrested everyone within that block."

I'm assuming that they're using the term "kettled" in a similar vein that the Germans used it during the Russian campaign ... Kesselschlacht ... as in "cauldron battle" .. where the enemy is completely encircled and forced to either face complete destruction or surrender.

It's a short leap from "cauldron" to "kettle", so, if you're the force inside the encirclement, you've been "kettled".