without saying goodbye.
Precisely the reason I will never go again. at least in the old days I could use I'm going to the cash point excuse.
Just go, tell them you have better shít to be doing the next day.
At the same time make a joke about them all being ****s, opening up that you don't like them and suggesting you would never socialise with any of them but for the fact that you work with them. Say this in a deadpan and serious way, but just as you go to leave do the wee gun motion and shoot them with both hands, creating the impression of humour and bonhomie.
You know you meant it. That is all that matters.
Be careful to not just walk to the pub next door or across the road as this may blow your story.