Go outside "for air". If already outside, go inside "to warm up". Give your otherwise obviously aimless wanderings a focus by going to the toilet, then going to the alternative toilet. While there, read a book on your phone. The Auckland Libraries app Libby is ideal for this and its selection of ebooks is surprisingly broad. I'm currently enjoying The Cool School: Writing From America's Hip Underground, which is mostly raw, recounted experience from some of the most celebrated cool lives of the 20th century - Miles Davis, Charlie "Bird" Parker, Warhol, Dylan - all of whom were once central to the American social scene. It's all the thrill of the party without the drag of actually being there.
Delay, delay, delay joining the party until the point at which you can delay no more, at which time you will be forced to confront your worst fears and sit at a table or in a semi-circular booth with six to eight people you know vaguely, who you can't hear over the music, but who keep trying to speak to you anyway.
Don't try to eliminate your discomfort. Locate the discomfort in your body, exist inside it and within it. You are the discomfort; the discomfort is you. Realise the discomfort is there for a reason, which is to make you feel bad.
Say to yourself, "I can get through this. I have gotten through this before." Accept the centrality to said endurance of toilets. Block out the fact you could watch the last four episodes of The Crown (series three) in the time you will spend here. Block out the fact life is made entirely and only of time and therefore this event is, in a very real way, killing you.
Block out your awareness of the improbable elasticity of time, which turned to a thick treacle as soon as you walked through the door - as you knew it would, as it always does - and into which you immediately sank chest-deep.
Look for someone with a shared interest in avoiding parties. You will recognise them because they will be waiting outside the alternative toilet. Latch onto them immediately, fiercely, physically if necessary. Clutch their sleeve, follow them to the bar, follow them back to the toilet. They will be your life raft. Laugh loudly at everything they say to make clear they are your friend and always will be. If they give you their cellphone number, text them right away. In the message field, write your name, followed by "New friend!"
If you have kids, after a while you can excuse yourself and say you have to go home to be with them. That's not a lie. It's illegal to leave your kids home alone. You really should have been onto this earlier.
Know you will wake in the morning into that glorious few seconds before your memories of the preceding night begin bubbling to the surface and you come to the dread realisation that, although it's a new year, it's not a new you, not as far as your attitude to parties goes. Your suffering will be thickest through these sticky summer nights, but you know it will stretch far beyond, years into our post-apocalyptic future, presumably unto eternity. Hell will be a party.
One day your kids might get married and expect you to attend. They will probably force you to sit alongside their new parents-in-law and expect the lot of you to get along. In that moment, you will wish for the sweet return of all the suffering of their babyhoods, the years in which they screamed for three to four hours every night and spent all day demanding to be entertained. You would give anything to somehow be able to use that bundle of havoc to preclude your attendance at the event and accompanying social gathering that will mark their official separation from, and rejection of, you.
In the face of all the social horror that lies ahead of you, having just woken up on New Year's Day 2020, your best option is to find a private place in which you can hyperventilate. May I recommend the toilet.