How to create a funny (and realistic) fake poster with ChatGPT

You probably saw the AI starter pack craze in spring 2025: little action figures in blister packs showing off our lifestyle, hobbies or bad habits, always with a touch of humour. Snow globes followed in the same spirit. Fun, yes. But ChatGPT‘s image generator can do much more than that: a fake poster that looks completely real.

I already use it to illustrate some of my articles, reworking scenes or ideas I couldn’t illustrate any other way. Whether it’s to freshen up an image, create a more telling atmosphere or simply get around the limits of stock photo libraries, ChatGPT often gives me exactly what I had in mind.

The key is the right prompt. Getting there takes a bit of trial and error, but once you have a prompt template that produces what you want, just like with the starter packs, the sky’s the limit.

In this guide, I’ll show you how to create a funny but believable fake advert and place it in a realistic setting, like a London Underground station. All without Photoshop.

My idea: a fake anti-odour campaign that looks real

The idea came from those slightly offbeat public campaigns you see on public transport. I wanted to invent one myself. Topic: body odour on the Tube. Anyone who has taken the Central line in August knows exactly what I mean.

So, a funny poster with a slogan that is cheeky but kind:

“Leave your mark on the world. Just not under your arms.”

The result: a realistic image of a backlit poster on the curved wall of a Tube station, with its Underground roundel and “Way out” signs. All generated from a single prompt.

What ChatGPT’s image generator can do

Image generation in ChatGPT isn’t limited to portraits. It can build complete scenes, with a fake poster that blends naturally into a coherent setting.

What impressed me:

• The poster is properly integrated into the scene, like a real advert.
• The text on the poster is clean and readable, with hardly any glitches.
• The style is close to a real urban campaign, with a quirky illustrated touch.

Above all, it comes down to a well-structured prompt.

A quick word on versions: when I first wrote this guide, the images came from GPT-4o’s image model. Since April 2026, ChatGPT uses Images 2.0 (the gpt-image-2 model), which is even better at writing legible text on images. Basic generation is free for everyone; the advanced “thinking” mode is reserved for paid plans.

That said, the image sometimes doesn’t quite match what you hoped for. Just talk to ChatGPT and point out what’s wrong: a misspelt word, a cropped poster, a detail out of place. It will generate a corrected version.

My prompt template for a fake poster

Here is the template I came up with. It’s easy to reuse for other topics:

Setting:
[e.g. A London Underground station. The poster is in a backlit advertising frame on the curved wall of a platform, with a few passengers waiting.]

Visual style:
[e.g. realistic with a humorous comic-book touch / realistic photography / semi-realistic]. The poster blends naturally into the scene, like a real advert.

Poster (graphic content):
[e.g. A body odour awareness campaign. A man in a suit raises his arm, revealing a sweat patch, and the passengers around him are fainting. The slogan sits at the top, the subtext below it and the signature at the bottom.]

Poster mood:
[e.g. funny but believable, bright colours, semi-realistic comic style]

Text on the poster (English only, clearly visible):
– Slogan: [”Leave your mark on the world. Just not under your arms.”]
– Subtext: [”The heat is rising. The smell doesn’t have to. One small gesture, a breath of fresh air for everyone.”]
– Signature: [”A campaign for fresher journeys on the Underground.”]

Just replace the parts in square brackets to suit your own topic. One tip: invent the brand or organisation behind your campaign rather than using a real logo. It’s funnier, and it keeps you out of trouble.

Another tip: choose a setting ChatGPT can draw convincingly. My first idea was a poster inside a Tube carriage, but ChatGPT kept making the carriage far too roomy, more like a commuter train than the cramped Tube. A poster on a platform wall looks far more believable. Then describe the poster itself precisely: what the picture shows and where each line of text goes. My first replacement bus poster left too much to ChatGPT’s imagination and came out unconvincing; once every element was defined, the result was spot on.

The result

Here’s what I got from a single prompt:

It’s expressive, funny, and it could easily pass for a real campaign on the Tube. That realism has a downside, though: it’s getting harder and harder to tell what’s real from what’s fake.

More ideas to try

You can adapt this template to dozens of other fake campaigns, just as punchy.

Human kibble at a railway station

Setting:
A busy London railway station. The poster is in a backlit advertising frame between two platforms, next to the departures board, with commuters rushing past, families with suitcases and someone clutching a meal deal.

Visual style:
Realistic photography, cinematic mood. The poster blends perfectly into the scene, with soft but believable lighting.

Poster (graphic content):
A bag of kibble that looks like dog or cat food packaging, but made for humans. The product is proudly displayed like in a food advert. The brand name “Crunchums” is written in a mouth-watering font. Next to the bag, a happy young man is eating some, cereal-advert style, biting into a piece of kibble with exaggerated delight.

Poster mood:
Absurd humour but visually believable
Bright colours, supermarket advert style
Serious, polished layout despite the silly idea

Text on the poster (English only, clearly visible):
– Slogan: “Finally, a kibble that gets you.”
– Subtext: “A complete meal. Crunchy. Vaguely human.”
– Brand: Crunchums®

An honest ad for the trains

If you have ever travelled by train in Britain, you know the dreaded words “rail replacement bus service”. Perfect material for a poster that is, for once, completely honest:

Setting:
A British railway platform on a grey, drizzly day. The poster is in a single backlit advertising frame on the platform wall. Two passengers wait nearby, seen from behind, holding umbrellas. Nothing else in the scene.

Visual style:
Realistic photography, natural daylight. The poster blends perfectly into the scene, like a real railway advert.

Poster (graphic content):
A photo of one white coach, seen from the side, parked in a rainy station car park. A handwritten cardboard sign taped at the bottom of the windscreen says “TRAIN”. The slogan sits at the top on a dark green background, the subtext just below the photo, and the signature in a dark green band at the bottom, next to a simple invented logo: a white circle with a stylised train inside.

Poster mood:
Dry British humour but visually believable
Muted railway colours, dark green and white
Serious, polished layout despite the silly idea

Text on the poster (English only, clearly visible):
– Slogan: “Why take the train when you can take the replacement bus?”
– Subtext: “Twice the journey time. Half the legroom.”
– Signature: “Britannia Rail. Getting you there. Eventually.”

You could also imagine “alternative” campaigns about working from home, open-plan office etiquette or phone calls on speaker in the quiet carriage. The template stays the same; only the message changes.

What next?

This kind of poster is ideal for:

• Starting a creative series of “posters we’d love to see”
• Sparking conversations (and smiles) on social media
• Practising your copywriting and visual skills without opening Photoshop

Conclusion

What I love about this exercise is that it mixes creativity, humour and technique with a lot of freedom. A few well-chosen lines, and ChatGPT does the rest. So if you have a message to get across, turn it into an imaginary street poster… and share it!

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