https://labs.openai.com/s/9YF5WxF1GoZVdzpLBAQYp2Zg
https://labs.openai.com/s/wBfHevs9hIZXvzkJ686mFmn3
https://labs.openai.com/s/M0i029fZnYjQXHFobUpw7eun (best of batch imo)
https://labs.openai.com/s/Hf4z0M9M3KBr6IaaKsjEt9Mx
A few more tries didn't manage to create any photorealistic shots with actual cucumbers-in-seats – perhaps due to the absurd contrasts required – but shifting to a 'cartoon' style with the prompt "editorial cartoon of the King of Belgium giving a speech to many cheering cucumbers, professional illustrator" got a lot closer:
https://labs.openai.com/s/4IonSKYkl0okhNvzJmEAH30K (good)
https://labs.openai.com/s/ZeadCzZ9WqeASYXPlOb13wDV (good)
https://labs.openai.com/s/nERf6bALKEBsQQBvPVsAH7o4 (good)
https://labs.openai.com/s/7dsZu3bwtfGZZxxJYtg9lTVf
If I had more time & credits to burn, I suspect working off those could eventually hit something really apt... but it takes some work & tinkering.