What are some examples of awkward sounding but grammatically correct sentences?
That that exists exists in that that that that exists exists in.
Jim opens a cafe selling fish and chips. He has a sign made. It arrives and it says "fishandchips". So he rings up the sign company and says:
You need to put more space between "fish" and "and" and "and" and "chips"
As far as awkward-sounding is concerned, I submit there are few sentences spoken in English that sound more awkward than:
Ed had edited it.
This is very hard to say in the rapid flow of conversation, and results in a sound something like:
Try it for yourself, speaking quickly, and you'll see what I mean.
Ending a sentence with a preposition is something up with which we will not put.
— Someone who was not Winston Churchill
I found John in an unenviable position.
there are the syllables "an", "en", "in", "on", "un" (i.e. all of "aeiou") run together. This makes it a little tricky to say.
How about some semantic awkwardness?
"Colorless green ideas sleep furiously" —Noam Chomsky
My grandfather's favorite is:
What noise annoys an oyster?
The article you linked has a few other examples of such sentences. As it says, "Any word that is both an animate plural noun and a transitive verb will work."
Try this one. Who polices the police? Police police police police. Who polices the police police? Police police police police police police. Etc.
You'll probably want to put some punctuation in these:
Wouldn't the sentence "I want to put a hyphen between the words Fish and and and and and Chips in my 'Fish and Chips' sign" have been clearer if quotation marks had been placed before Fish, and between Fish and and, and and and and, and and and and, and and and and, and and and and, and and and Chips, as well as after Chips?
James while John had had had had had had had had had had had a better effect on the teacher.
I know this one:
Time times time times time squared equals time times time times time times time