I was on the the this flight last night (should have been yesterday afternoon, but turned into last night...), albeit in First while the incident occurred down the back.
There was a series of events that caused the delay. It started with two families boarding the plane with infants not fit to travel with one of them having Chicken Pox, and while their offloading was taking place, the incident with these youngest began.
I was getting reports from the one of the FA's but didn't realise they were joking about having a bomb on board until the captain mentioned something about having a wife and two kids at home and had no intention of taking any chances, although he didn't specifically mention the threats (that I read in the media before we even took off).
In any case, at least a couple of these guys seemed drunk to me even at the check in area, and were singing loudly as they approached the gate, and being a little obnoxious.
One of the guys was wearing a Fur robe (I have a photo in fact...) and while anyone is free to dress as they like, who wears that when it's 35 degrees outside???