Start telling a long and rambling story that in no way relates. Keep talking until interrupted.

Help me formulate the dullest response to colleagues

Now if there was ever a job for an LLM like ChatGPT, this is it

I've quit a toxic workplace before - I just said "it's a bad commute". Nobody can really pick at that reasoning since everyone has way too many personal variables for commutes (even from adjacent houses) to be comprable.

"You! You're the reason I'm quitting. Yeah, you're just kind of a shithead, you never do anything, you just kinda run your mouth all day long and I can't fucking stand it. Like an unbuttered piece of toast thinking it's interesting..."

Just say, “I don’t feel passionate about this work and I want to look for something that I find more fulfilling.”

Tell them your shoes are getting old and you’re too lazy to buy new ones, and coming to work is just wearing them out more

The colour of the walls irritates me.

You're kinda asking non German people how to deal with German people I'm not sure you'll get what you're looking for here

"I got an offer I couldn't refuse." and leave it at that! The offer might as well be just 'not having to deal with you guys anymore'.

Just say personal reasons. Even if they're nosy and keep pushing, in that case they're clearly in the wrong to any sane person looking on, because it's normal to not want to share your deepest most personal problems with your coworkers.

"well, with how things are going.."
"You'll find out soon enough"
"You know about mice and ships..?"
Refuse to elaborate further.

"I'd rather not say". Repeat this single answer until they desist.

A bearded stranger told me to throw away a ring.

The water is too crunchy here.

They caught me pissing in the water jug from the kitchen. Shrug. Guess I'm out.

Say something like:

“It’s best not to discuss such details at this time”

Which will tell them, yes, there is a good reason, no, I can’t tell you since I don’t trust you.

You will never get in trouble for something like that since you literately are not saying anything.

The bonus part is that if the coworker is cool, they can just reach out to you a week or two after you left and you can be honest if you think they are worth it.

Just start crying everytime and say nothing. They will get unconfortable and leave.

Say you make more money from your Only Fans. I just makes more sense to do it full time now.

I won the lottery.

My mental health can't handle this bullshit.

I had an opportunity I couldn't pass up.

I have to care for my father/mother/aunt/dog.

I want to travel and see the world.

I hate you.

I hate (insert random coworker/boss here.)

My wife/husband is taking care of me.

Onlyfans makes more than here.

Since you are from Germany, simply say "Die Grünen sind Schuld". Everyone will understand and accept this reason.

"I found something better, but I'm not able to divulge what it is at this time. "

Or

"You! You're the reason I'm quitting."

"I won the lottery! No, you can't have any."

Or, Give each of them a different reason and watch them go crazy trying to figure it out.

Assuming they don't know what you'll be doing after?

Say "found a new opportunity."

You could be headed into unemployment and that'd still be a businesslike and no nonsense reply.

My cat has asthma, we're moving to a drier climate.

It's the triple boring combo of pets, manageable illness, and moving.

"oh damn, you guys didn't know? I feel bad for you but it's probably too late for you now. Guess you'll find out soon enough."

Then: complete radio silence.

Say you are working for a family member (helping your dad with his company or sth.). A colleague once had to go help his parents with their small company and no one questioned it a bit. No "better pay?" or "man you are moving far away!" just "oh, well good luck".

Go with the standard politician non-answer: "to spend more time with family". I have no idea if German politicians give the same stock response though!

"They were getting too close to figuring it out."

“New job pays X euros more” and make up random number. That’ll shut em up

There are already a lot of good answers here, so instead I’ll offer you a game you might enjoy.

For context, I used to have the same problem, but I stumbled into a hack that turns it into a fun pastime rather than a nuisance or concern, and now it’s one of my favorite parts of taking up a new post.

What: Seed your own wild rumors by baiting known gossips with decoys.

How: While I’m often surprised by which rumors have legs, it seems prompt technique is the key controllable factor. Prompts that are more off-hand, indirect, and opaque seem to cultivate rumors with better proliferation and more colorful embellishments. I’m not sure why less is more here, but my theory is that the more gossips have to make up, the more they “own” their version of your story and the better they are at selling it. If necessary, you can drop some facts here and there (use only truths) but in general try to avoid details. Gossips are insanely good at filling these in on your behalf.

Who: This part is easiest. Gossips will always come to you. Usually they are some of the first people to approach you at your new job, looking for the scoop. The first you meet are usually the defacto gossip leads, but the rest reveal themselves quickly, especially if your rumors are good. You will learn to recognize them by the way they sidle up in the break room or pry opportunistically in conversation, however the easiest sign is that they respond to evasiveness and deflection in the opposite way others do.

Why:

1. Reconciling their conflicting versions of your personal story and private life disrupts their rumor mill internally and erodes their legitimacy externally.
2. You have the unique pleasure of receiving, over time, fragments of “your story.” This has utility for tracing the leaks and determining network composition, but mostly it’s just hilarious to see what they come up with, and interesting to know the versions of you that people will entertain.
3. As to social risk, so far none of my rumors have developed into anything terribly embarrassing — usually what they come up with is far more interesting than reality, sometimes even flattering — but the few times I’ve had to correct a story in conversation it was met with instant acceptance of the more realistic take. Most people know to take hearsay with a grain of salt.
4. I suppose the gossips might be mad if they realized you were toying with them, but I suspect they would just treat you as a dry well and leave you alone, which also solves your problem.
5. It’s relatively victimless as mischief goes. You don’t even have to lie. In fact it works better if you don’t.
6. And it requires almost no effort.

TL;DR: You can bait the nosy nellies into writing fan fiction for you. It’s easy, fun, and good for the environment. Your personality traits make you a natural at this game —others might need to tone down their instinct to overshare or practice being pointedly vague — but if in doubt just remember, storytelling is the gossips’ job and you are their humble yet beloved muse.

Put on a painfully sad face and say that you/someone in your family has medical issues and that you don't want to speak more about it.

Because HR and I do not agree on what constitutes sexual harassment, so I choose to take my talent elsewhere.

I need a sabbatical. Canada maybe or New Zealand. A retreat to a monastery also sounds nice. I will rebuild an old farm house. Something along these lines. :)

It doesn't have to be the truth, or does it?

Just pull a Grandpa Simpson.

If you risk people yelling at you for stopping, simply tell them there's too much yelling and drama for you.

Also if you have paid sick leave you could simply get ill depending on where you are and on union agreements at least here where I am, the employer has no right to know why you are sick. Just that you are. After a certain number of days/weeks they can ask for a doctors notice that you indeed can't work. But still the proof does not need to explain your illness. It just needs to confirm that you are not able to work. Most doctors will understand the strain of having to be somewhere where youre under this sort of pressure