I don't know why or how, but reading that comment suddenly made me get it even though I said the exact same thing in my head multiple times... I am not a smart person.
After some googling, I found out it's from a Dr. Seuss book. That crap was never popular in my country, so "omg don't tell" is quite ridiculously stupid. People from other countries who haven't read the book couldn't get it.
One fippht two fippht red fippht blue fippht
two fifth
red fifth
blue fifth
-ut the fuck up