The plural of Kleenex should be Kleenices.

I call them "tissues." Calling all tissue Kleenex is like my mom calling all video games Nintendo.
- FWIW, I just learned that escalator and kerosene started as trademarked brand names.
  
  So did Frisbee
- insisting on calling all tissues kleenex is how the company loses the rights to the name

My parents do say kleenices, but they're massive nerds. And linguists. Dad has bad allergies so "Did you take the kleenices out of your pockets?" was a common laundry time question. They also pluralized pizza as "pizzot".
- Fun fact! Pizza is already plural. The singular is a piz, which is where we get the English word “piece”, because pizza come pre-portioned. The word “peace” also comes from the same derivation, because it is impossible to go to war while enjoying a piz of pizza.
  /s

Kleenex is the name of the brand, not the tissues
- Brands are nouns and can (and are) thus genericized.

According to the internet the -ex to -ices is a dead suffix for specifically latin borrowed words
- is a dead suffix
  sure, if you go with that attitude!

Kleenpodes!
Yes, I know its unrelated. I'm just trying to force in the whole octopi problem.

Furthermore, it should be pronounced like it was a Greek philosopher.
- Κληνίσης

Obviously pronounces "Clean-eh-keys" right?
- As a crazy person that took 5 semesters of Latin, absolutely, but it's a battle in which I've admitted defeat, much like "as per."
  If English made any sense, "matrices" would be the normal plural and pronounced with the italianized soft c. But then "indexes" is over there being irksome.
  I think the correct plural here is simpler: a zero plural, i.e Kleenex. Probably because we just elide the entire word "tissues."