Meaning of "Proofreaders Rule! O Q?"

I was listening to a rerun of the BBC panel game “My Word”. In his story, Frank Muir describes a t-shirt with the saying “Proofreaders Rule! O Q?” This got a moderate laugh from the audience, so they obviously got the joke.

I sure didn’t. I thought it might be related to some proofreader’s mark relating to a question mark (from the “Q”), but Googling on “proofreader question” didn’t turn anything up. Could someone please enlighten me?

Thanks in advance.

It’s blindingly obvious, and you may kick yourself after this.

It’s simply
“Proofreaders, rule, OK?”
Spelt incorrectly, and in need of a proofread!

Maybe the "**** rule, OK? joke isn’t as well known in the US?

My favourite: “Dyslexics rule, KO”

C’mon UK dopers, lets have some more!

OK Sauce rules, HP?

Queen Elizabeth II rules, UK.

Thesauruses rule, OK, certainly, right, sure.

I’m bored. :slight_smile:

Misspellers of the world, untie!

Did you hear about the dyslexic pimp: he bought a warehouse.

Dyslexics of the world, untie! You have nothing to lose but your snaich!

Did you hear about the dyslexic insomniac seminarian who sat up all night pondering the meaning of dog.

:smack:

Did you hear about the dyslexic warloc who sold his soul to Santa?