The Indiana Jones "Bog Off" Door Hanger
It's well-known that YS was compelled to change the wording on the door-hanger to "Push Off" to avoid giving offence (to whom, they were never told. Indiana Jones, possibly). But equally ghastly was the fact that on every sample issue they received that month, when you took the sellotape off the door-hanger, the print was torn off as well. Horrified, YS expected to be swamped with complaints. There wasn't a single one. They concluded that either it was just the sample batch that was rubbishly put together, or (more likely), everyone thought it was their fault the print was pulled off when they undid the thing. Jonathan Nash was told this story* after spoiling five or six back issues in an attempt to send someone a door-hanger (they thought it was their fault the print was etc etc). There's now a single unbesmirched copy left in the world, possibly the one that will part cleanly with its cheap plas-like gift. It's a bit like Schrodinger's Cat (except everyone knows it won't work).
*Jonathan (displaying half-dozen ruined placky strips): Hang on - what's going on here?