Being a language teacher, of course I've gotta get technical.
There is another meaning to 'Scotch'
scotch
(skɒtʃ )
Word forms: 3rd person singular present tense scotches , present participle scotching , past tense, past participle scotched
verb
If you scotch a rumour, plan, or idea, you put an end to it before it can develop any further.
They have scotched rumours that they are planning a special London show. [VERB noun]
...but local residents are trying to scotch plans to add an extra terminal. [VERB noun]
Synonyms: put an end to, destroy, smash, devastate.
In other words you could read it as 'destroy all jokes]
I know that usage well, as a high percentage of the settlers of The British-founded provinces of Canada were Scots, and the others were English, Welsh and Irish, all of whom would make fun of The Scots. However, I didn't think that would apply here, because, if the jokes in this book are tainted, the title should read: "Scotch
ed Jokes", or "Scotch These Jokes".