Wiktionary
vb. (context idiomatic English) To attempt to control the uncontrollable.
Usage examples of "herd cats".
He had managed to get a single voice out of that chaos of conflicting personalities, even though for the most part it was like trying to herd cats and just as thankless a task.
And although they didn't set out to give the money away to the poor, that was nevertheless what they did (if you accepted that the poor consisted of innkeepers, ladies of negotiable virtue, pickpockets, gamblers and general hangers-on), because although they would go to great lengths to steal money they then had as much control over it as a man trying to herd cats.
Small wonder that they themselves are some of the most quarrelsome groups aroundtrying to get various eco-groups together is like trying to herd cats.
You were at the ceileighe, Ericgetting two Bards to do anything together is like trying to herd cats!