If you opt for something, or opt to do something, you choose it or decide to do it in preference to anything else.
If you opt out of something, you choose to be no longer involved in it.
If you can opt in to something, you are able to choose to be part of an agreement or system.
I've thought opt is a sort of txt language before I had consulted the word with Google dictionary.
Some urban dictionary refers the term as Oriental People Time and " On The Piss".
Not a nice interpretation.
