There is NO PLURAL for to or too in the english language .
I think I said that...
'To' is a preposition and has no plural form, and 'too' is an adverb and also has no plural form, but all of them having the same form in shorthand will be interchangeable and have a plural form, therefore the sentence can in fact be written that way and no other way and be a correct sentence.
Of course it isn't new, I didn't make it up, but I did get the answer when I heard the riddle. It is a sentence that can be spoken but not written in English, but it can be written in shorthand.
If you don't understand why the answer given is the correct answer, then there is no more I can do to help you. You either understand it and refuse to admit it or are unable to understand it.
I am not sure I believe that you were ever in a college English class though with the way you type. But, at any rate, you did not get the answer. Good try though. Maybe next time.

You seem to be the only one that doesn't understand the answer. Maybe the problem isn't the question, maybe it's you.
I'd be interested in contacting this professor though if there is one, what is his name and the name and location of the school he teaches at? It's obvious he never took shorthand either though so it might be an educational chat for him as well. Looking forward to hearing the information.
If you would like the entire sentence written for you to be able to understand, download the Gregg shorthand dictionary online, it will be enlightening for you I think.
Thanks for playing and thanks for the information concerning the professor in question.