A book mark would be better!
The pattern
This still is filed under Image carries the claim.
Define
One image does the entire argument. Copy, if any, is a caption, not a second ad.
Mechanism
Pictorial claim. The picture is readable as a sentence. If we need a paragraph, we picked the wrong picture.
Verdict
The idea is visual and the surface is a poster, a feed, or a silent frame.
Why it works
The poster never states the offence, it stages an exaggerated version of it, so the reader identifies the real behaviour themselves and feels caught rather than lectured. The word better does the whole persuasive job because it implies the comparison instead of naming the fault, which keeps the tone light enough for a library wall. Formally it is built for three screen passes, one flat yellow field, one blue line that describes the book with no fill at all, one black figure and one red accent shared by the iron and the words, and the switch from hard-cut red caps to loose black script is what makes the line read as a spoken aside rather than a rule.
Steal this when
Use this when you need to correct a small everyday behaviour without moralising: dramatise an absurd overstatement of it and let the reader supply the connection to what they actually do. The caps-then-script pairing is the device to copy whenever a headline needs to end in a human voice instead of an instruction.