How odd, and definitely no fun

I still think yours makes a promise, ours gives an instruction!

nanaej, I'm almost sorry you posted that explanation of flashing and grinning...could have kept us speculating for hours....!

I liked old instructions on jam pots 'pierce with pin and push off'

Not as exciting as the secret life of paint, but:
I could never understand the instruction on bottles of squash to "Dilute to taste" - surely it tastes much stronger when not diluted?

phoenix found this on a DIY website!!

Grinning ThroughPrevious paint can still be seen beneath the new coatingTo avoid: Apply paint evenly. Avoid brushing out too much. Apply further coats

FlashingPatchy uneven appearance of the coating when looked at from different anglesTo avoid: Apply paint quickly and evenly. Avoid touching up after initial application

There you go, I knew that some of you might think I was making it up! The packet of Polyfilla that Mr P was using definitely says "No flashing or grinning"

Slightly different wording to the product that Anagram looked at, as that one seems to give a certain reassurance that the product will neither expose itself or indulge in unseemly smirking, whereas ours seems to be some sort of instruction as to how to behave whilst using it.

(Is it just me, feel free to tell me if you think I'm a bit weird/odd/delete where not applicable, or on second thoughts don't, as I'm a bit concerned about the current state of my mental health.)

I bought, "24 wooden clothespegs. Ideal for pegging out your clothes" from Wilko.

DIY is so dull!

Intrigued by the OP, I had a look at one of OH's tubs of ready-mixed filler, and noted that the makers claim their product:

Will not flash or grin
Resists slumping

You don't know what it might do!

Poster: 'Ideal Eyes'
Underneath: 'Buy one get one free'.....

And 'This door is alarmed'
...I hope it doesn't get frightened..........

A bag of peanuts– "may contain nuts". One hopes so.