This had me in hysterics...thanks for the chuckle, you serious gentleman you!

Monstrous/monstrosity
Pompous/pomposity

Porous / Porosity

Along the same lines, judge / judgment (drops the e)

But not Devious / Deviosity.

Humorous/humorosity
Glamorous/glamorosity
Ridiculous/ridiculosity

Here's one I'd not seen before: gratitudity.

That doesn't even sound correct.
Try to use that in a sentence please?

A gratitudity of 18% will be added to bills for all parties of 10 or more.

Platitude/platitudity
(No shizz?) that's a new one for me.

"The platypuss' nudity was fraught with platitudity."

On the subject of spelling mistakes . . . platypuss?

Ha-ha...I'm blaming my phone's spell check for this one.
Kudos for the correction.

I read this in the comments section of an article on
stem cell research discussing the growing back of lost
teeth from urine samples.

"I would like to voluntear for this study.
I have bin wading a long time for sumthing like this."

Volunteer, although I can see why he is in tears
after losing some teeth.

Ispell is a free program for spell checking. With it downloaded, you just need to type your message, click on tools at the top of the page. Ispell will open a window showing each misspelled word which you can change.

Offly.

As in, You're offly sensitive today.

Or just use a browser (like Firefox) that automatically checks your spelling as you type. In Firefox you can select this in options>advanced in the tools menu.

You should always try to improve one's vocabillary ...

Bob,
Then we get into the spellchecker mistakes that are auto-generated on your smartphone. I'm guilty of those. Actually, my phone's guilty; I've just failed to proofread.

In Al Schneider's wonderful "The Theory and Practice of Magic Deception" he has the line, "the thundering heard invests more in what they say ..."

I wrote this off as a foible of Spellcheck, but chuckled at the inadvertent pun. I even felt somewhat excused for similar errors passed over in self-editing some of my eBooks.

but later in the book the same replacement of "heard" for "herd" was made -- and I now wonder.

Di the first acceptance of the phrase by the software make it seem natural the next time around? If so, it supports AL's theory about how the human mind "routers" information.

Did Al do this deliberately to use the pun as re-enforcement of the concept of our visual blindness?

Did he do it deliberately to test our intellectual laziness?

Three options (maybe more) that all support in a different way why magic works.

....

and I just realized the pun works the other way -- "the politician herd our requests"

What about the obvious explanation that Al simply misspelled the word?

Twice? That is what Spellcheck is for isn't it? To catch spelling errors and offer alternatives. Isn't that what editors are for?

It is also possible that Al doesn't know the difference between the words or assumes the reader does not.

None of those options are "obvious" to me.

Based on conversations I have had with Al I suspect he knows and deliberately left it in - whether the first error was intentional or not is unknown.

Regardless, it is my opinion that the way our mind deals with errors and puns is similar to how we deal with magic effects.

If someone actually reads my mind or just pretends to I can be equally astonished.

Occam's Razor- the simplest explanation is the most likely. Also note that Schneider's book was released in 1998. It may be a mistake to assume that he used spell check or even a computer when he wrote it.