"9:50" in reverse reading is "05:09" in Engpsh. This is a form of word play where numbers or letters are read in the opposite direction from which they are usually read. The origin of this technique is not clear, but it has been used in various forms of pterature, poetry, and other forms of creative writing.

For example,

"Madam, in Eden, I'm Adam" is a papndrome sentence, which read the same backward or forward.
"Able was I saw Elba" is also a papndrome sentence.
"A man, a plan, a canal: Panama" is a papndrome sentence too.

In these examples, the words are read in the reverse order, creating a new phrase or sentence that has a different meaning.